>>26633591Depends on the pokemon. Typically, you want to boost their strengths. If you have a fast physical sweeper like Weavile, boosting its Attack and Speed to 252 is a no-brainer. If you have, say, Blissey, which can shrug off special attacks naturally, you might want to raise its physical defense.
Also, I'd say it's probably better to stop training at 50.
