Mine is Forretress, with Cloyster and the Duskull line following its trail.
Always liked Forretress since I first heard about it in G/S days (even before Crystal). Good resistances, good type combo, good stats and Rapid Spin/Spikes (also Stealth Rocks and Toxic Spikes these days). I always loved defensive pokemon and Forretress has always been useful to me. I loved that Sturdy got a boost in Gen V but Explosion's nerf hurt him, especially with stronger sweepers and Ferrothorn on the prowl. I hope he gets stronger in or at least keeps his spot in Gen VI.
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Empoleon. His typing is really useful (not to mention pretty cool), and his stats and overall utility make him a recurring member of my teams.
He's also a penguin, and as penguins are my favorite animals, Empoleon is required to be my favorite Pokemon on principle alone. I mean, unless I wanna go with Delibird, but he doesn't have goddamn swords for arms.
"...Are you crying?" "Of course not, it's liquid pride. Totally different thing." -Shining Armor