Dr. Mario- Dr. Mario is a clone of Mario. He has the same attacks, but they look different. For instance, instead of throwing Fireballs, he throws Megavitamins. He is also a well-rounded characters, but it's a bit boring having Dr. Mario, Mario, and Luigi all in the same game with almost the exact same moves.
Mario- Mario is back for more smashing in this amazing Super Smash Bros. sequel. Most of his attacks are the same, but they look much much cooler. Mario is a good well-rounded character, though his Fireball can be quite annoying. His Super Jump Punch will knock you senseless and centless.
Luigi- Luigi may not be a clone of Mario, but most of his attacks are the same as Mario's. All except for his Green Missile attack. Luigi is faster, and he has a very effective Super Jump Punch which acts like a Fire Punch when he uses it in an enemy's face. Luigi's taunt is the strongest, most powerful attack in the game when it hits someone...
Bowser- It's about time we had someone like Bowser join the fun. Like DK, he is slow, but hard to smash off the platform unless he has really high damage. His attacks look awesome and bring out the true Bowser. The Bowser Bomb is sort of like the Yoshi Bomb. He'll show you what the words "brute strength" mean. The king of Koopas may be slow, but very, very strong.
Peach- Peach is a very unique character. She gets to use Toad as her shield (poor toad), and she can float for a short while. Also, Peach can use a Parasol. She is easily thrown, and her attacks are pretty weak. One of her cool attacks is pulling Vegetables from the ground and throwing them at her opponents.
Yoshi- The green dinosaur has made his way on SSBM. His egg moves aren't that powerful, like in the original Super Smash Bros. He can still swallow other characters and incase them in an egg, and he can throw an egg. He can now use a move called Egg Roll, which is very fast. Yoshi only has two jumps, (no triple jump) so on his second jump, while in the air, he cannot be smashed.
Donkey Kong- He's bigger, faster, stronger too... DK is one of the strongest characters in this game. Watch out for his new and improved Giant Punch. It sure can pack a wallop. His Spinning Kong is more effective than in SSB. He's fairly slow, but hard to throw of the platform.
Capt. Falcon- Capt. Falcon is a very fast character when it comes to running. His attacks are very strong, but some of them take a short while to use. You might have to wait a few soconds to use the Falcon Punch, but Falcon Kick is faster and can be used as a long range attack.
Ganondorf- Ganondorf is the clone of Capt. Falcon. He may not run as fast as Falcon, but he is just as strong. His Warlock Punch is slow but very powerful. Also, the Wizard's Foot is just like Falcon Kick. Usually the cloned characters are better than the people who they are cloned from, but in this case that's not true. Ganondorf is ugly and slow, so he's not a great choice for beginners. Though as a computer player, he makes a tough opponent.
Falco- As the clone of Fox, Falco has the same types of moves. Fox is much faster than Falco, but Falco is a much higher jumper. His Reflector shield can reflect any projectile attack, including items thrown at him. When things bounce off the Reflector shield, they come back with twice the strength. Falco's Blaster is stronger than Fox's and makes people flinch.
Fox- Fox is an extremely fast character, though none of his moves are all that powerful. He has most of the same moves as in SSB, but his Blaster doesn't even make people flinch. The Fire Fox is better, especially the look of it. Also, Fox's new move is called Fox Illusion which allows him to move really quickly, and leaves blue images of Fox behind.
Ness- The little phychic is back. He's ready to hit more homeruns with his baseball bat. All of his special attacks are phychic based, which include: PK Fire, PK Flash (his new attack), PK Thunder (PK stands for Psycho Kinesis) and PSI Magnet, his shield that absorbs projectile attacks. Ness still has his Yo yo!
Ice Climbers- Popo and Nana, play as two people but one control in this game. Though they can both be KO'd separately, only the Ice Climber you are controlling, counts against your stock. They do their attacks together, such as the Belay, when they jump on top of each other to reach higher places. Most of their attacks are associated with their hammer. They can shoot a beam of ice out of it, and spin around quickly, perfect for knocking opponents off the stage.
Kirby- The little pink puffball is ready for some major flattening. (Kirby's favorite hobbies are making pancakes and vacuuming.) He may not look strong, but Kirby is a great choice for smashing your opponents beneath the ground! He is very strong, and well-rounded, but he is very light. Kirby's Stone attack can turn him from being a lightweight into a 100 ton heavyweight (or one of five different things including a Thwomp) temporarily. He also has his "trademark move," Swallow, which gives him the ability to use other players' "B" moves by stealing their power. By doing this, he also gets their head gear. Many of his moves are enhanced, and he has some new ones from games like Kirby 64 and Kirby's Adventure.
Samus- Samus has returned to SSBM as well. She can drop Bombs, shoot out Missiles (her new attack), and she still has her Grappling Beam. Samus still has her protective armor (which doesn't seem to do much), and many familiar faces from Metroid games will appear in SSBM. Her opponents may be strong, but they are no match for Samus' Charge Shot.
Zelda- Zelda is unlike many of the other characters in this game. She is actually two characters in one. By using her Transform attack, she can turn into Sheik. Zelda can reflect projectile attacks with Nayru's Love, and use the same attack as a weapon too. Zelda has many magical attacks to help her in fights such as Din's Fire or Farore's Wind. Sheik- Sheik is more acrobatic and faster than Zelda. She can also Transfom into Zelda, and vice versa. Sheik has a few long-range attacks like Needle and Chain, but she laks magical ones (the only magical attack she has is Vanish). Together, Sheik and Zelda each have their own set of moves which makes them a really good choice for battle.
Link- Link can throw Bombs and he has his Boomerang like in Super Smash Bros. His Spin Attack attack is much more effective in smashing people off the stage, and boosting Link up high as part of his triple jump. His Bombs hurt himself and his shield can stop a few projectile attacks. He can charge up his Bow; the more he charges it, the harder and faster the arrows go.
Young Link- Young Link is Link 7 years ago. All of his attacks are identical to Links except that he has a Fire Bow instead of a Bow. Young Link is quick and defensive so he makes a great choice for battle. He can jump from wall to wall like Falcon, Samus, Mario and Fox.
Pichu- Pichu is the clone of Pikachu. With all of the same moves, they both seem equally good. But they are not. Pichu is actually much worse than Pikachu. Every electric attack that he uses will do damage to himself. Though, when pichu uses his Thunder, it will only hurt him if the thunder bolt actually hits him. If he is standing under a platform, it will not do damage to him.
Pikachu- Pikachu is a pretty light character, but he is very quick. His lightning attacks are powerful, so you should try running around the stage, and choosing the right moments to attack. Most of Pikachu's moves are the same as in SSB, but they look better and they are better. People who are familiar with the yellow Pokemon from SSB are in for a real shock in this sequel.
Jigglypuff / Purin- Jigglypuff (Purin is her Japanese name) is a very unique character. She has six jumps, but no B Up jump that boost her upwards, though her Pound attack can boost her sideways which is very useful for her Target Test. By Singing, she can put someone to sleep, and then by using Rest, she can smash her opponent very far, but she falls asleep. She is very slow and a lightweight.
Mewtwo- Mewtwo is a very powerful hidden character. He can charge up his Shadow Ball, Disable a person, then Disabling them again causing them to blow away. He can Teleport, and reflect back attacks by using his Confusion attack. When Mewtwo lifts someone or something up, he uses his mind, which allows him to run pretty fast while holding an item such as a Barrel.
Mr. Game & Watch- He is as flat as a piece of paper, and has many tricks up his sleeve. 9 different attacks can be executed from his Judgement attack. Game & Watch can shoot sausages out at people using Chef. Two firemen can give him a boost to safety, and he can catch projectile attacks with Oil Panic, and after he catches 3 he can unleash its power. In all, Mr. Game & Watch is a very confusing character, who is very powerful, initially from the game system titled Game & Watch.
Marth- Marth is from the Japanese RPG Fire Emblem. He is is strong and quick, but he has no projectile attacks. His sword does the most damage when it hits enemies with its tip. You can charge his Shield Breaker move that can break through any character's shield and damage unshielded enemies greatly. 4 different attacks can be linked up using Dancing Blade, which make him glow a different color during each attack. His Dolphin Slash is very quick.
Roy- Also from Fire Emblem, Roy is the clone of Marth. Most of his attacks are the same as Marth's, but they are fire based. For instance, his Blazer move is quick, but it lights people on fire when it hits them. Using his Counter attack, (Marth can also do this) right before an enemy hits him, he blocks the enemy's attack, and smashes them back. Roy's Flare Blade attack is much more powerful than Marth's Shield Breaker, but it does 10% damage to himself. It's worth it though, because a fully charged Shield Breaker does 50% damage to his opponent, smashes them a long way, and breaks their shield if they try to block it.
Dr. Mario- Dr. Mario is a clone of Mario. He has the same attacks, but they look different. For instance, instead of throwing Fireballs, he throws Megavitamins. He is also a well-rounded characters, but it's a bit boring having Dr. Mario, Mario, and Luigi all in the same game with almost the exact same moves.
Mario- Mario is back for more smashing in this amazing Super Smash Bros. sequel. Most of his attacks are the same, but they look much much cooler. Mario is a good well-rounded character, though his Fireball can be quite annoying. His Super Jump Punch will knock you senseless and centless.
Luigi- Luigi may not be a clone of Mario, but most of his attacks are the same as Mario's. All except for his Green Missile attack. Luigi is faster, and he has a very effective Super Jump Punch which acts like a Fire Punch when he uses it in an enemy's face. Luigi's taunt is the strongest, most powerful attack in the game when it hits someone...
Bowser- It's about time we had someone like Bowser join the fun. Like DK, he is slow, but hard to smash off the platform unless he has really high damage. His attacks look awesome and bring out the true Bowser. The Bowser Bomb is sort of like the Yoshi Bomb. He'll show you what the words "brute strength" mean. The king of Koopas may be slow, but very, very strong. 
Peach- Peach is a very unique character. She gets to use Toad as her shield (poor toad), and she can float for a short while. Also, Peach can use a Parasol. She is easily thrown, and her attacks are pretty weak. One of her cool attacks is pulling Vegetables from the ground and throwing them at her opponents.
Yoshi- The green dinosaur has made his way on SSBM. His egg moves aren't that powerful, like in the original Super Smash Bros. He can still swallow other characters and incase them in an egg, and he can throw an egg. He can now use a move called Egg Roll, which is very fast. Yoshi only has two jumps, (no triple jump) so on his second jump, while in the air, he cannot be smashed.
Donkey Kong- He's bigger, faster, stronger too... DK is one of the strongest characters in this game. Watch out for his new and improved Giant Punch. It sure can pack a wallop. His Spinning Kong is more effective than in SSB. He's fairly slow, but hard to throw of the platform.
Capt. Falcon- Capt. Falcon is a very fast character when it comes to running. His attacks are very strong, but some of them take a short while to use. You might have to wait a few soconds to use the Falcon Punch, but Falcon Kick is faster and can be used as a long range attack.
Ganondorf- Ganondorf is the clone of Capt. Falcon. He may not run as fast as Falcon, but he is just as strong. His Warlock Punch is slow but very powerful. Also, the Wizard's Foot is just like Falcon Kick. Usually the cloned characters are better than the people who they are cloned from, but in this case that's not true. Ganondorf is ugly and slow, so he's not a great choice for beginners. Though as a computer player, he makes a tough opponent.
Falco- As the clone of Fox, Falco has the same types of moves. Fox is much faster than Falco, but Falco is a much higher jumper. His Reflector shield can reflect any projectile attack, including items thrown at him. When things bounce off the Reflector shield, they come back with twice the strength. Falco's Blaster is stronger than Fox's and makes people flinch.
Fox- Fox is an extremely fast character, though none of his moves are all that powerful. He has most of the same moves as in SSB, but his Blaster doesn't even make people flinch. The Fire Fox is better, especially the look of it. Also, Fox's new move is called Fox Illusion which allows him to move really quickly, and leaves blue images of Fox behind.
Ness- The little phychic is back. He's ready to hit more homeruns with his baseball bat. All of his special attacks are phychic based, which include: PK Fire, PK Flash (his new attack), PK Thunder (PK stands for Psycho Kinesis) and PSI Magnet, his shield that absorbs projectile attacks. Ness still has his Yo yo! 
Ice Climbers- Popo and Nana, play as two people but one control in this game. Though they can both be KO'd separately, only the Ice Climber you are controlling, counts against your stock. They do their attacks together, such as the Belay, when they jump on top of each other to reach higher places. Most of their attacks are associated with their hammer. They can shoot a beam of ice out of it, and spin around quickly, perfect for knocking opponents off the stage.
Kirby- The little pink puffball is ready for some major flattening. (Kirby's favorite hobbies are making pancakes and vacuuming.) He may not look strong, but Kirby is a great choice for smashing your opponents beneath the ground! He is very strong, and well-rounded, but he is very light. Kirby's Stone attack can turn him from being a lightweight into a 100 ton heavyweight (or one of five different things including a Thwomp) temporarily. He also has his "trademark move," Swallow, which gives him the ability to use other players' "B" moves by stealing their power. By doing this, he also gets their head gear. Many of his moves are enhanced, and he has some new ones from games like Kirby 64 and Kirby's Adventure.
Samus- Samus has returned to SSBM as well. She can drop Bombs, shoot out Missiles (her new attack), and she still has her Grappling Beam. Samus still has her protective armor (which doesn't seem to do much), and many familiar faces from Metroid games will appear in SSBM. Her opponents may be strong, but they are no match for Samus' Charge Shot.
Zelda- Zelda is unlike many of the other characters in this game. She is actually two characters in one. By using her Transform attack, she can turn into Sheik. Zelda can reflect projectile attacks with Nayru's Love, and use the same attack as a weapon too. Zelda has many magical attacks to help her in fights such as Din's Fire or Farore's Wind.
Sheik- Sheik is more acrobatic and faster than Zelda. She can also Transfom into Zelda, and vice versa. Sheik has a few long-range attacks like Needle and Chain, but she laks magical ones (the only magical attack she has is Vanish). Together, Sheik and Zelda each have their own set of moves which makes them a really good choice for battle.
Link- Link can throw Bombs and he has his Boomerang like in Super Smash Bros. His Spin Attack attack is much more effective in smashing people off the stage, and boosting Link up high as part of his triple jump. His Bombs hurt himself and his shield can stop a few projectile attacks. He can charge up his Bow; the more he charges it, the harder and faster the arrows go.
Young Link- Young Link is Link 7 years ago. All of his attacks are identical to Links except that he has a Fire Bow instead of a Bow. Young Link is quick and defensive so he makes a great choice for battle. He can jump from wall to wall like Falcon, Samus, Mario and Fox.
Pichu- Pichu is the clone of Pikachu. With all of the same moves, they both seem equally good. But they are not. Pichu is actually much worse than Pikachu. Every electric attack that he uses will do damage to himself. Though, when pichu uses his Thunder, it will only hurt him if the thunder bolt actually hits him. If he is standing under a platform, it will not do damage to him.
Pikachu- Pikachu is a pretty light character, but he is very quick. His lightning attacks are powerful, so you should try running around the stage, and choosing the right moments to attack. Most of Pikachu's moves are the same as in SSB, but they look better and they are better. People who are familiar with the yellow Pokemon from SSB are in for a real shock in this sequel.
Jigglypuff / Purin- Jigglypuff (Purin is her Japanese name) is a very unique character. She has six jumps, but no B Up jump that boost her upwards, though her Pound attack can boost her sideways which is very useful for her Target Test. By Singing, she can put someone to sleep, and then by using Rest, she can smash her opponent very far, but she falls asleep. She is very slow and a lightweight.
Mewtwo- Mewtwo is a very powerful hidden character. He can charge up his Shadow Ball, Disable a person, then Disabling them again causing them to blow away. He can Teleport, and reflect back attacks by using his Confusion attack. When Mewtwo lifts someone or something up, he uses his mind, which allows him to run pretty fast while holding an item such as a Barrel.
Mr. Game & Watch- He is as flat as a piece of paper, and has many tricks up his sleeve. 9 different attacks can be executed from his Judgement attack. Game & Watch can shoot sausages out at people using Chef. Two firemen can give him a boost to safety, and he can catch projectile attacks with Oil Panic, and after he catches 3 he can unleash its power. In all, Mr. Game & Watch is a very confusing character, who is very powerful, initially from the game system titled Game & Watch.
Marth- Marth is from the Japanese RPG Fire Emblem. He is is strong and quick, but he has no projectile attacks. His sword does the most damage when it hits enemies with its tip. You can charge his Shield Breaker move that can break through any character's shield and damage unshielded enemies greatly. 4 different attacks can be linked up using Dancing Blade, which make him glow a different color during each attack. His Dolphin Slash is very quick.
Roy- Also from Fire Emblem, Roy is the clone of Marth. Most of his attacks are the same as Marth's, but they are fire based. For instance, his Blazer move is quick, but it lights people on fire when it hits them. Using his Counter attack, (Marth can also do this) right before an enemy hits him, he blocks the enemy's attack, and smashes them back. Roy's Flare Blade attack is much more powerful than Marth's Shield Breaker, but it does 10% damage to himself. It's worth it though, because a fully charged Shield Breaker does 50% damage to his opponent, smashes them a long way, and breaks their shield if they try to block it.