As much as I like the little guy (especially its movepool), its stat distribution is pretty poor. Namely, it only has a BST of 440, and what would really help it is more HP and physical defense. If Gamefreak let it have a BST of 500 (+60 to its base stats) and divided it evenly between its HP and defense, it'd be used a lot more. Here's hoping for an (unlikely) evolution that won't fuck up its other good qualities.Well then, let's change that.
I think Kecleon is very underappreciated. While he doesn't have the highest attack, he has a very respectable attack stat, amazing special defense, and a ridiculously huge move pool, Nasty Plot egg move making even special sets viable. Kecleon is a lot of fun to use. His ability is easily manipulated, but still pretty awesome.
If it had better durability, I would be on board with using it. It really does have a stellar movepool for support and physical attacking on the side, and don't forget that HG/SS added Recover to its movepool.