I, personally, am a gargantuan fan of Mega Blastoise. It looks quite epic when it comes to design, in my opinion. Its body is extremely bulky, it's got one huge cannon stuck onto its back which it could take in and out of its shell at will, and it has two mini-cannons attached to its hands alongside. Mega Blastoise makes a great battler as well. Its defensive stats are very high, and so is its Special Attack stat. Plus, with its Mega Launcher ability, it gets an additional boost to some special-based moves that it has access to. Chesnaught would have to be another of my favorites. I have one on my team at the moment, and it's able to wall my opponents pretty easily. Along with Chesnaught and Mega Blastoise, I like Talonflame, too. :]