I caught a Sunkern (Nicknamed it trachy) and am trying to max out it's Pokeathlon stats. But when one goes up, one or two go down! How do I fix this?
No it's Game Freaks way of keeping the balance.Thats why there is a team of three so you don't have one strong Pokemon that you'll keep on reusing.
You cant have them all maxed out in the game, otherwise you could do it three times and win too easily.
It is impossible to do so. So, that means you can't. (even though your Sunkern is named Trachy)