Golden Sun: The Lost Age Summons only
ZAGAN 
+ 
Location: In the Indra Cave. Use Move and Release in order to get summon tablet.
MEGAERA + 
LOCATION: In the Osenia Cavern, in the heart of West-Osenia. Use Scoop on the X at the right side of the cavern, then follow the stairs down.
FLORA +
Location: Inside Ayer's Rock. When the statues are activate, go to the room with three red dots in it.
MOLOCH + 
Location: Inside the Madora Ruins, with Reveal, Tremor and Frost.
ULYSSES +
Location: Izumo Ruins. You need Sand in order to Freeze all puddles near the entrance. Then you need Dry, too, to dry up the last small pond.
HAURES +
Location: In the West-Angaracavern. You need to have Isaac and co. with you, because you need to use CARRY.
ECLIPSE +
Location: Win at the fountain at Lemuria (just like in Tolbi).
COATLICUE +
Location: In the very south of the continent of Atteka in a cavern. You need a flying ship in order to reach the cave, then use Dry.
DAEDALOS +
Location: Defeat Valukar in the Yanbi Desert Underground Cave in order to get this combo tablet.
AZUL +
Location: Defeat the Star Magician in the Cave of Treasure Island in order to get this tablet.
CATASTROPHE +
Location: Defeat Sentinel in the Islet Cave. You must have Teleport in order to get this tablet. Remember, Sentinel is immune to Psynergy, but vulnerable to Summons, Djinn and Fysical Attacks
CHARON +
Location: Right at the entrance of the Djinn Dungeon/Anemos Sanctum in the town with the big crater on the continent of Ateka. You need to capture ALL 72 Djinn first.
IRIS +
Location: Defeat Dullahan of the Djinn Dungeon/Anemos Sanctum in the town with the big crater on the continent of Ateka. Dullahan is very tough, so be prepared. This freaking boss has over 16544 HP and he can whipe up your party in only 2 turns using Charon and Formina Saga against you. You need to capture ALL 72 Djinn first to enter.