It's kind of weird-something-athlon.
There are 5 courses: Speed/Stamina/Jump/Power/Skill (which makes 10 minigames total)
Each Pokémon has in HS changed contest stast from D/P/Pt to these new PokéAthlon stats. It's both quite fun and quite hard to get through all challenges. AND quite neccessary if you want a trainer stars.