Lee's ability to copy his opponents allows him to match their appearance, skills, and to a degree, even strength. This sometimes works to Lee's disadvantage when he copies a weaker opponent. Lee and Chan have been training together for years, and they have become like brothers in that time.
"He's one of the trainees who's always at the Dojo. His name is Lee. He's like an older brother to Chan. Lee respects the Master above all else and hangs on every word he says." - Goombario (Paper Mario)
"It's Lee disguised as me. His Max HP is 20. Do I really look like that? No way... He'll use Heabonk and Tattle. He has the same skills as me. Of course, I'm much better looking and more debonair. And I hope that I'm stronger!" -Goombario (Paper Mario)
The mysterious Lee is The Master's most advanced student, and he'll change forms as he attacks. If you begin the battle by using Goombario's Tattle, Lee will match the tactic, giving Mario a free turn to wallop away. - Paper Mario Player's Guide
Attack Pattern: Lee can copy the form of one of his opponents, and he will also copy their attacks. When in his regular form, he does a flying headbutt attack. Depending on how far into the game you are when you fight him, his regular form is probably more dangerous than the form he copies.
Basic Fighting Strategies: You should be able to use the Action Command by the time you fight Lee. If you come straight from Star Hill to fight him without learning to time your attacks using the action command, you will probably have a hard time winning. He will assume the same form as your companion (not Mario) so choose one who you think you can defend against. Keep in mind that you will have to defend against as many hits as your companion can make after using the action command. For example, if Lee assumes Goombario's form, you will have to block two Headbonks in a row.
Advanced Strategies: If Lee copies Goombario, he may use Goombario's "Tattle" move. The Player's Guide claims that this happens as soon as you have Goombario use Tattle on Lee, but in my experience it just happens randomly. In his regular form, Lee uses a dangerous flying headbutt. You can block this by pressing A just as he hits Mario.
