Party member

Mario has had many partners during all his adventures, all of whom help him during many points of time. Luigi also gets partners in Paper Mario: The Thousand-Year Door, though the player cannot play as them, for Luigi is not a playable character in the game.

Mario & Luigi series Characters

 * Mario
 * Luigi
 * Baby Mario
 * Baby Luigi
 * Bowser

Super Mario RPG: Legend of the Seven Stars Partners

 * Mallow
 * Geno
 * Bowser
 * Princess Toadstool

Paper Mario Partners

 * Goombario
 * Kooper
 * Bombette
 * Parakarry
 * Lady Bow
 * Watt
 * Sushie
 * Lakilester

Paper Mario: The Thousand-Year Door Partners

 * Goombella
 * Koops
 * Flurrie
 * Yoshi
 * Vivian
 * Bobbery
 * Ms. Mowz (optional)

Paper Luigi Partners

 * Blooey
 * Jerry
 * Torque
 * Hayzee
 * Screamy

Super Paper Mario Partners

 * Peach
 * Bowser
 * Luigi

Pixls

 * Tippi
 * Tiptron (Replaces Tippi) (Optional)
 * Thoreau
 * Boomer
 * Slim
 * Thudley
 * Carrie
 * Fleep
 * Cudge
 * Dottie
 * Barry (Optional)
 * Dashell (Optional)
 * Piccolo (Optional)

Trivia

 * Despite the fact that Toads are common and notable NPCs in these games, Mario has yet to get a partner who is a Toad.