While I don't mind Characters having badges in SMBW, at the same time I want to bring back the trope of every character having different abilities and weaknesses, so here we go:

Mario- He's the most balanced the bunch of course

Luigi- He has his iconic Flutter Jump, but he also has traction problems.

Peach- She can float in the air, but she's kinda slow

Daisy- She's the lightest character, which can lead to longer jumps, but her ground pound is weaker

Yellow and Blue Toad- They are the fastest characters

Toadette- She's the only character who took some proper swimming lessons lol

Rosalina- She can attack enemies with the Spin Attack from SMG, BUT she's the tallest character and she can't fit in tunnels that are more than 1 block tall (her ducking sprite would be 1,5 block tall)

Wario- He can Attack Enemies with his Arm Dash thing from the Wario Land Series (only in Small and Big forms like Rosalina in SM3DW), but he jumps pretty low.

Waluigi- He can Double Jump! But he's the worst character when it comes to swimming.

Bonus Game Modes:

Yoshi- He controls the same way as in Super Mario Wonder, BUT he can both take power-ups and damage.

Me! (Domix)- I'd control the same way as characters in SMB2/USA, a.k.a. I'd be able to throw and ride on enemies, but won't stomp them. (Also, is it bad to add Self-inserts to fangames?)

Nabbit- He controls the same way as Mario, but he can't take either damage or Power-ups. The true easy mode.