I recently picked up a copy of this game, and i am I am interested in speedrunning it in the near future. However, I am relatively unfamiliar with the game’s mechanics, so would someone mind explaining to me the gameplay differences between the two?

There's some camera bugs with zitz, and a few other extra bugs exclusive him. I would say start as rash since that's the main character runners play as. My point is a lot more people play as him.

Thanks for the response! I assume outside of those bugs, they control exactly the same? (Top speed, attack power, etc) I know that in battlemaniacs that rash and pimple control differently, so I wanted to know if there was a similar situation with this game

I think game mechanics wise the characters are identical.

Yes, they control exactly the same. Looking back I should have said that before lol.