Queen Slime candidate:
I know we already have two mario related songs but the Paper Mario series is different enough that I feel like it might be worthy of an exception (especially this particular entry as it's musical style is pretty unique and it's highly unlikely anyone else will pick it due to how... unpopular it was)
I picked this song because it just
sounds like a slime theme due the bizarre and silly selection of instruments they used but also sounds serious enough for a boss which can potentially stomp you into the ground with pure chaos.
Windy Day candidate:
I'll be honest, I'm not sure why I picked this one. It might be a bit too... tranquil and eerie for a windy day theme? But something about it does work. I'm not sure how to really describe it. I didn't use this in my personal wavebank so I can't say how well it suits the event ingame.