Why the Goomba should win: The power of positive thinking. Yup, that's the best we could come up with, or more importantly, the power to think at all. Plastic can't think, but Round One established that the Goomba has a brain. Maybe the Goomba will come up with an ingenious plan or something?
Why the green note should win: As we've already stated, the Goomba's primary strategy in the first round was heavily rooted in fighting a zombie and not be made out of meat. It's fairly unlikely that more of the same will pay off against the green note (which is not a zombie) in round two. Without even doing anything, the green note starts at an advantage.
The green note doesn't need to change strategies; it's made of nearly indestructible plastic. Oh, and Goombas don't have hands. That makes it unlikely that a Goomba could even hit a green note. Looks like point, game and match to the green note, but just so we're absolutely sure, let's use this chart:
Above: Wow, what an upset!
Verdict: Goomba Wins!
Why the infected Bidoof should win: The parasitic Flood has fully taken hold in the Bidoof from the last fight. That means the unstoppable nature of the Flood and the indifferent awkwardness of a Bidoof have been combined into a creature slightly more intimidating than a squirrel - that’s pretty serious for this tournament.
Why the slime should win: Although the slime is made of goo and, most likely, very sticky, the infected Bidoof is just as gooey. As science tells us, if you combine two sticky things they cancel each other out: gum in hair can be removed with peanut butter and peanut butter in your neither-regions can be dealt with by applying glue. It's a simple and perfectly explainable process.
The Slime obviously counters the sticky factor that the Flood contamination has added to the Bidoof, and the Bidoof will die because you can't de-flood a Bidoof without killing it. If you de-slime a Slime, there's always more slime underneath. If that didn't make sense, don't try to rethink it - there's no time. Accept what happened and keep reading.
Verdict: Slime wins!