Lee is a Duplighost and a student at the Toad Town Dojo, as seen in Paper Mario. He trains under the Master with the Buzzy Beetle Chan. Lee is the Master's most advanced student and acts like an older brother to the Chan, the weakest student. Lee also has deep respect for the Master, but does not worship him like Chan does. Although he is the Master's most advanced student, Mario did not have a difficult time defeating the Duplighost and earning the Second-Degree Card.
Since Lee is a Duplighost, he has the ability to transform into Mario's partner. Using this ability, Lee acquires the appearance, skills, and (to a certain degree) offensive and defensive capabilities of the copied party member. However, this technique is actually his biggest disadvantage. In fact, Lee has a higher attack in his normal form than in any copied form. Additionally, he will only assume the form of Mario's current companion. That means that Mario can exploit the weaknesses of his companions after Lee has copied him or her. For example, if Lee copies Goombario, the Duplighost will occasionally use the Tattle ability, which does not damage Mario and does not help Lee in any way.
Lee will attack as many times as Mario's partner would attack if he or she used the Action Command, meaning Mario needs to defend that many times. For example, if Lee copies Goombario, the Duplighost will attack twice when using the skill Headbonk because Goombario attacks twice with Headbonk when he uses the Action Command.
"This is Lee, of the Dojo. He's training under The Master and is happy to fight us.He has mastered the art of disguise, so don't let it faze you when he suddenly mirrors us. Remember, he can't stay disguised forever. Don't let his strange tactics throw you off guard, no matter how many times he transforms."  As Mario's partners
"It's Lee disguised as me. Do I really look like that? No way... He'll use Headbonk 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!"
"This is Lee disguised as Kooper. Lee has disguised himself as Kooper perfectly, so his attack power is the same as Kooper's usual power. Just like Kooper, he attacks with his shell. If you flip him over, you'll beat him with ease. Incidentally, Lee's red scarf and wristband look cooler than Kooper's. ...Don't tell Kooper I said that, though."
"This is Lee disguised as Bombette. Lee has disguised himself as Bombette perfectly, so his attack power is the same as Bombette's usual power. Sure, he looks cute as Bombette, but he packs a punch!"
"This is Lee disguised as Parakarry. Lee has disguised himself as Parakarry perfectly, so his attack power is the same as Parakarry's usual power. He's usually slow, but once he's in battle, he's a whirlwind of feet and feathers. He's a sight to behold in the heat of battle. To tell the truth, I think he's the most intimidating one on our team!"
"This is Lee disguised as Bow. Lee has disguised himself as Bow perfectly, so his attack power is the same as Bow's usual power. That Smack attack is brutal! So cruel!"
"This is Lee disguised as Watt. His Max HP is 20, so you should be serious even though he looks as adorable as Watt. Lee has disguised himself as Watt perfectly, so his attack power is the same as Watt's usual power. Remember, don't stomp on him! You'll get a massive electric charge if you do."
"This is Lee disguised as Sushie. His Max HP is 20. Sushie looks tough! Think she'd be mad if she heard that? Lee has disguised himself as Sushie perfectly, so his attack power is the same as Sushie's usual power. I'm not too thrilled to have to fight Sushie. She's strong!"
"This is Lee disguised as Lakilester. His Max HP is 20. If I remember our battle with the real Lakilester correctly, this one seems to be weaker. Lee has disguised himself as Lakilester perfectly, so his attack power is the same as Lakilester's usual power. Dodging that Spiny Flip is tough, so pay attention."  Trivia