I know Mario got a surprise oddball character already with Piranha Plant, but I've been thinking about this for a while and I genuinely feel like it'd be a hilarious WTF character to include.
...
Toadette and Peachette as a transforming character. No, Toad isn't involved at all. I thought of a concept for this and I'm feeling wild enough to share it right now so here goes nothing I guess!
Toadette acts as the base. She's on the weaker side, and is also stubby and very light. She has decent (but not exceptional) ground movement but horrendous jump height and air movement (a bit better than Steve, but not by much).
Her "gimmick" is that, ~35 seconds into the match, Toadette gets access to the Super Crown. By pressing Shield + B, she transforms into the super-powered Peachette! The catch is, unlike other "transform" characters,
she cannot go back to her Toadette form.
You wouldn't really need to either. Peachette is almost a straight upgrade from Toadette, the only flaws being her bigger size (making her more susceptible to being hit) and a bit less ground acceleration. Her air movement, like in the game, is exceptional. Her moves are souped up versions of Toadette's, mixed with some funny twists on Peach's moves. For example, Dash attack is Peachette's attempt at Peach Bomber, but she ends up falling flat on her rear.
If she doesn't transform back though, how does Peachette's OPness balance out? Well, like a Powerup in the Mario series, opponents will have to beat it out of her. Suffering more than 50% damage as Peachette knocks the Super Crown right off her head, transforming her back to the mediocre Toadette.
And she's stuck with it until next stock. The Super Crown can only be accessed once per stock, so be strategic.
That's it I guess..! Wow. That was way too long of a tangent for a character nobody freaking likes
I do however feel like this pair is just a perfect WTF addition that would drive the Internet absolutely crazy, and I kinda love that.