Assist characters are called to the stage when a player grabs the Summon Cube. Unlike Super Smash Bros., where many of them are from obscure/unpopular games that weren't able to merit a playable one, they are all characters from shows the playable ones are from.
These are as FollowsEdit
Johnny Bravo He come on her moto and speak. Only on 3DS (his a playable character on XL).
Cheese (Foster's Home) Goes around screaming
Coco (Foster's Home) Lays eggs
Dee Dee (Dexter) Dances
Dracula (Grim Adventures) Starts a dance party making characters dance
Eduardo (Foster's Home) Runs around trying to hug everyone
Fred FredBurger (Grim Adventures) Runs around trying to hit people with his frying pan
Fuzzy Lumpkins (Powerpuff Girls) Shoots people with his meat gun turning them into meat
Gazpacho (Chowder) Throws pickles everywhere that heal You
General Skarr (Grim Adventures) Has his army of tanks come and try to KO you
Gwen Tennyson (Ben 10) Sheilds the character that summons her
Madame Foster (Foster's Home) Imaginary Friends chase her, damaging foes. Only on PTE XL.
Major Glory (Dexter) Freezes other characters and flies away.
Mandark (Dexter) Goes around shooting lasers
Mung Daal (Chowder) Falls and leaves food that can heal you
Number 2 (Code Name: Kids Next Door) Goes on a plane from the show flying across the screen twice
Number 4 (Code Name: Kids Next Door) Does a series of punches and kickes. Only on PTE XL.
Panini (Chowder) She latches on a random character that reverse there controls.
Schnitzel (Chowder) When hit he'll wobble in place and cause damage (like Wobbuffet From Smash Melee And Brawl)
Stickybeard ( Kids Next Door) He will get a giant cannon that will hurt anyone and fires a giant gumball.
Val Hallen (Dexter) He fires lightning his guitar everywhere
Vreedle Brothers (Ben 10) They fire their guns everywhere hurting everyone