I want a Pokemon with a lots of stat changing moves so I can use them to stat boost the Pokemon then use Baton Pass to give to another good or legendary Pokemon
The obvious answer is Smeargle. Smeagle can sketch any move (bar a few), and therefore it can learn all of the stat boosting moves and baton pass. In addition it can put your opponent to sleep with spore, so you can get the boosts. Also, smeargle has the hidden ability moody, so one of its stats sharply raise every turn, with one stat decreasing by one stage.