Alright, first off: the Mega Mushroom theme sounds EXACTLY like it'd be a Silvagunner track.
Besides that, the powerups are great (granted, i wish the mini mushroom and gold flower were swapped around), Mario getting the Red Star when he enters a NiGHTS stage is genius, and SRB2Persona support just turning the game into an amalgamation into Mario RPG, M&L, and Paper Mario is genuinely amazing. Hopefully we get a Luigi somewhere later down the line.
Second off, here's some of my gripes:
Personally, I'd prefer if there was option to set dive to a separate button, since I either have to choose between only being able to dive odyssey style or not being able to change direction in the air while using my hammer.
It'd be a lot more convenient if the "hey stinky" emote could be moved to a button rather than being chat-only. Also, hitting anything that's relatively high in the air with a flower-type powerup is a pain. Maybe make it so that you can change the trajectory by moving the camera up or down?
Besides all that, pretty good character. I would recommend.