Goomy - Know Your Dragons

Nope, sorry. Mega Gyarados is Water/Dark instead, bizarrely enough.

Gyarados isn't a dragon either. You'd think this would be a huge water/dragon snake-like pokemon with huge scales after evolving from its water-type magikarp, wrong! It actually gains the fly type.

Logic fixed with gen 6 tho, both have a way to become dragon-type instead of fly-type with a mega-evolution.