All the Character Roster you have seen, ARE FAKE!
The Official 24 Character Roster will not be Released until after April 4th at the Earliest.
All these other Ones are just some Kids Desperate for Attention.
The Characters that we know for Definate that are in, Are as Follows:

Starting Roster:
Mario
Luigi
Princess Peach
Yoshi
Toad
Koopa Troopa
Baby Mario
Baby Peach
Wario
Waluigi
Bowser
Donkey Kong

Unlockables:

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