how broken would a grass/dragon mega serperior w contrary and draco meteor be?
Hmm. Well, Serperior is pretty good now with just Contrary, Leaf Storm, and basically no other special movepool to speak of, and Grass has terrible type coverage. The only other point of comparison is Malamar’s Superpower, which is a lot weaker for several reasons. I don’t know if it’d quite be broken broken because un-STABed Draco Meteor isn’t going to be that much better than Leaf Storm a lot of the time, but it’d definitely be top tier.
EDIT: Derp, misread the question. Eh, a Grass/Dragon mega evolution would be strong, but I don’t think *that* much more ridiculous than a bunch of other mega evolutions, and you get eaten alive by Ice Shard. Also, would Serperior actually be able to learn Draco Meteor anyway? Only Dragon-types can use the move tutor, and Ampharos can’t, despite having a Dragon-type mega evolution.