Party member

Mario has had many partners during all his adventures, all of whom help him during many points of time. Mario and his partners as a group are generally referred to as a party, as the event of a character joining is referred to as said character "joining your party." 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 - The youngster from Goomba Village who travels with Mario.
 * Headbonk - Headbonks target twice (0 FP)
 * Tattle - Will analyze the enemy (discovering their HP), and will open text about the enemy (0 FP)
 * Charge - Increases next Turn's ATK by 2 (1 FP)
 * Multibonk - Headbonks target multiple time (3 FP)
 * Kooper - Joins Mario after he gets him his shell.
 * Shell Toss - Shoots Kooper's Shell at one ground enemy (0 FP)
 * Power Shell - Strikes all ground enemies with Kooper's Shell (3 FP)
 * Dizzy Shell - Makes target dizzy (4 FP)
 * Fire Shell - Strikes all ground enemies with Kooper's Shell on fire (5 FP)
 * Bombette - After freeing her from the cage in Koopa Bros. Fortress, she joins Mario.
 * Body Slam - Body Slams a ground Enemy (0 FP)
 * Bomb (attack) - Bombs a ground enemy (3 FP)
 * Power Bomb - Bombs all ground enemies (6 FP)
 * Mega Bomb - Bombs all enemies (8 FP)
 * Parakarry - After Mario finds Parakarry 2 letters, Parakarry decides to ally with him and collect letters along the way.
 * Sky Dive - Parakarry, while airborne, kicks an enemy (0 FP)
 * Shell Shot - Parakarry, uses his shell for a more powerful attack (3 FP)
 * Air Lift - Can lift enemies out of Battle (3 FP)
 * Air Raid - Flies around at a hyper pace damaging all enemies (6 FP)
 * Lady Bow - Forces Mario too take a deal; if she and Mario defeat Tubba Blubba, she'll give him the 3rd Star Spirit, Skolar.
 * Smack - 3-5 times, hits an enemy (0 FP)
 * Outta Sight - Makes Mario invisible, making him unable too take damage (skips Bow's next turn, 2 FP)
 * Spook - Scares enemies away (3 FP)
 * Fan Smack - Hits an enemy 5 times with more power than Smack (5 FP)
 * Watt - Joins Mario when he saves her from the Big Lantern Ghost.
 * Electro Dash - Attacks an enemy piercing Defense
 * Power Shock - Paralyzes target enemy (2 FP)
 * Turbo Charge - Ups Mario's ATK by 1 for a # of turns (3 FP)
 * Mega Shock - Paralyzes all enemies (5 FP)
 * Sushie - Joins Mario after he saves her in the Jade Jungle.
 * Belly Flop - Jumps on enemy (0 FP)
 * Squirt - Shoots Water at target (3 FP)
 * Water Block - Ups Mario's DEF by 1 for a # of turns (3 FP)
 * Tidal Wave - Throws a wave of water at all enemies (6 FP)
 * Lakilester - Former minion of Huff N. Puff, joins Mario after his girlfriend Lakilulu successfully convinces Mario to spare his life.
 * Spiny Flip - Throws Spiny Egg at target.
 * Spiny Surge - Throws many Spiny Egg's at all enemies.
 * Cloud Nine - Gives Mario a chance to dodge an attack for a # of turns (4 FP).
 * Hurricane - Blows enemies out of Battle.

Paper Mario: The Thousand-Year Door Partners

 * Goombella - An archeology student at the University of Goom, Goombella is searching for the same Legendary Treasure as Mario and decides that it is in their best interest to work together.
 * Koops - Koops's father hadn't been seen since he'd gone off to challenge the ferocious dragon Hooktail. After hearing that Mario and Goombella planned to launch a fresh assault, he decided that he wanted to join them to prove to everyone (particularly his girlfriend Koopie Koo that he could be tough like his dad.
 * Flurrie - Madame Flurrie was a retired actress, just dreaming of coming out of retirement when Mario and friends asked for her help with a small task. She found their stories of adventure alluring, and decided that she would come with them to help as much as she could.
 * Yoshi - This baby Yoshi hatches from an egg that Mario found outside the Glitz Pit. He could be any one of a variety of colors and the player can name him.
 * Vivian - Once a member of the villainous Shadow Sirens, Vivian decides that Mario is much more deserving of her help than her sister Beldam is.
 * Bobbery - Admiral Bobbery had refused to go out to sea after a tragedy in his past. Mario must learn his secret to convince him to serve as navigator on a journey to Keelhaul Key, and he joins Mario's party after the ship's crash.
 * Ms. Mowz (optional) - A dashing badge thief, Ms. Mowz and Mario cross paths a number of times before she asks him to find a badge for her. Unknown to him, it was a test of his abilities--and once he passes and proves himself to her, she'll join the party and lend her treasure sniffing abilities to the heroes.

Paper Luigi Partners

 * Blooey
 * Jerry
 * Torque
 * Hayzee
 * Screamy

Super Paper Mario Partners

 * Peach - Joins Mario when she discovers she is a Hero of Light. She can duck under her umbrella, blocking most attacks, and she can also use it to float through the air.
 * Bowser - Joins Mario when he is convinced by Peach. He has twice the Attack of Mario, Peach & Luigi and can breathe fire.
 * Luigi - Joins Mario when found in The Underwhere; can Super Jump.

Pixls

 * Tippi
 * Tiptron (Replaces Tippi) (Optional - Sold by Francis after Chapter 8's completion for 999 coin's; the most you can hold at one time)
 * Thoreau
 * Boomer
 * Slim
 * Thudley
 * Carrie
 * Fleep
 * Cudge
 * Dottie
 * Barry (Optional - Unlocked by completing Chapter 3 and returning to the start of it and speaking to him)
 * Dashell (Optional - Unlocked by completing Flipside Pit of 100 Trials)
 * Piccolo (Optional - See Piccolo for unlocking instructions; a long list of errands)

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.
 * Every female partner in Paper Mario: The Thousand-Year Door kisses Mario.
 * All Paper Mario games that use the partner system have a Goomba, Koopa, and Bob-omb partner.