Cool topic! I've never thought about my favorite from each type...
Dark - Honchkrow: What a gangster, am I right? Not only are birds epic by nature, but this guy has a fedora. Pretty sure if pokemon were real, I'd have this guy, and we'd go to the casino together.
Fire - Camerupt: I love the dust that swirls when it drops into battle. I can see taking long rides through the country on its back, as long as those volcanoes were kept under control. What a beast.
Dragon - There's actually not one dragon type that I really, really like. I'd probably go with Vibrava because it's pretty cool looking.
Ice - Froslass: I always think it's really cool when pokemon evolve by gender. Have to make sure your Snorunt is female so you can get this icy lady. Seems like she'd be good to talk to, despite a cold personality.
Bug - Yanmega: I mean, is it a a dragonfly or a machine/helicopter? Looks like a cross between those. I can see threatening a bully with a dragonfly and them laughing, only to freak out when they see this beast come out.
Steel - Technically Magneton since it's now part steel, but I only think of it as electric. I'll say Durant, even though it's part bug. Durant is the coolest ant I've ever seen. Between Durant and Yanmega, I don't think people would mess with my bugs.
Psychic - Kadabra: Going old school here. Love the bent spoons, but you only need one (hear that Alakazam?). Two could prevent mobility and other attacks. Plus, who wants to have to trade their pokemon to get it to evolve?! Honorable mention to Natu/Xatu for being straight up cool and Gardevoir for being, well, Gardevoir.
Grass - Virizion: Taken me a long time to find a grass type that I really like, but found it in White 2. The combination of fighting solves two types I don't usually have. Another one I could see taking rides in the country side with.
Rock - Bastiodon: I can kind of see this guy as like an epic dog pet. It would be fun to have around the house and could keep you safe in a jam. Plus, use iron defense a few times and laugh as anybody tries to knock you out. Honorable mention to the amazing duo of Lunatone and Solrock <3 Just try to mess with me with the moon and the sun on my side.
Ground - Hippowdown: Come on, it's a hippo. One of the beastliest creatures in real life has to be a beastly pokemon.
Water - Kingler: One of my all time favorites, ever since the epic anime moment where he steamrolled through the first round of the Pokemon League. Hop on the big crab's back and travel the seven seas.
Fighting - Hitmonlee: Maybe it's the former soccer player in me, but I like that this guy kicks his way to victory.
Flying - Drifblim: Again, it's basically a hot air balloon people. There's not much cooler than that. Plus, it has ghostly tendencies. Too cool.
Poison - Muk: Another one I loved during the Pokemon League tournament. Only second to Kingler's epic run is the moment when Muk suffocates Bellsprout. Winner winner.
Normal - Ditto: So I can have any of my other favorites.
Electric - Magneton: My all time favorite. Love this guy. Tri-attack looks so cool. Brosef for life.
Ghost - Mismagius: Just a bad lady here. Is she a witch for Halloween? What's the story? We all want to find out, that's all I know.