Discworld: CMOT Dibbler
My Little Pony: Friendship is Magic: TGAP Trixie

I'd go for "whoever does most pull-ups wins," and I think I would do one and it would do zero and I would win

I'd go for "whoever is able to ride this horse the farthest distance in a minute wins," and I think I would ride it a few feet and it would not be able to ride a horse and I would win

I'd go for "whoever can stand on one foot the longest wins," and I think I would stand on one foot for about thirty seconds and it would not be able to at all and I would win

I'd go for "whoever can lie down on their back the flattest" and I would lie flat on my back, and the centaur would try its best but still have horse torso thickness and kind of flailing horse legs to contend with and I would win

I'd go for "who can kayak the furthest" and I would paddle for a few dozen feet and it would not be able to fit its bottom half into a kayak and I would win

in wales they call it "crisp and dale: rescue wardens"

✅ get turned into a pooltoy
✅ squeak
✅ creak
⬜ be thrown in the pool
⬜ float around aimlessly
⬜ squeak some more
⬜ get turned back (optional)