My personal favorite is Clefable.
It undoubtedly has the best movepool.
Persian is the fastest, Zangoose is the strongest, and Clefable is more balanced defensively. Clefable's ability allows it to do awesome stuff. With magic guard, it is unaffected by a burn, poison, leech seed, weather, recoil, and other stuff.
Clefable can spam all kinds of crap that would otherwise get you killed.
Here's an attacking set:
IPunchStuff (Clefable) @ Life Orb
Ability: MAGIC GUARD
-Fire Punch
-Ice Punch
-Thunder Punch
-Double Edge
You take no recoil from Double edge or the life orb, which is nice. Then you get awesome coverage on everything else. Here's a special attacking set:
IkillStuff (Clefable) @ Life Orb
Ability: MAGIC GUARD
-Thunderbolt
-Ice Beam
-Flamethrower
-Hyper Voice
Kind of the special version.
What I really like about Clefable is you can really make it your own. If you want different coverage, you can give it Shadow Ball, Focus Blast, Psychic, Signal beam, SolarBeam, among other things. It also has access to annoying Toxic, Thunderwave, and can be good support with Wish and Aromatherapy.
Clefable, FTW.
