Underrated: Blastoise
I feel blastoise is a lot bulkier than people realize. He can do a lot of things including being an anti lead with fake out and rapid spin to being purely defensive with counter and mirror coat.
Numel: bring him a couple of baton pass boosts and the opponent is done. Ive swept even water pokemon with this thing.
Overrated: Umbreon
I hate this thing so much... most pokemon that can do its job do it much better. Not to mention its attack stats suck, its not overly good at walling either. Id much rather run vaporeon or suicune.
Gardevoir: Apparently im not running into any good gardevoir trainers, ive never had any real trouble dealing with it. Was never really overwhelming, you can still ko past reflect or light screen, mostly the same thing over and over again. W-o-w looks nice on it though.
Glaceon: Not really feeling it, i mean having one of the most powerful ice beams in the game is nice and all, but i feel its stats are too awkwardly arranged for its full potential. That being said, a choice scarf can fix its speed, but youre still locked into one move.