The first thing that popped into my head for this CAP was Psychic typing. It doesn't offer resistance to any entry hazards or weather, though it does have a fantastic resistance to Fighting-type attacks. There are some great Psychic STAB options out there, like Psystrike, and while there are few that are risky on their own (Edit: Psycho Boost being a notable exception!), I think that one critical factor about them is that some popular Pokemon, those with Dark typing, are completely immune. Not only that, but these Pokemon also get STAB with Pursuit, which, of course, is super effective against Psychic-types.
(Edit: Also, there's the U-Turn weakness!)
For best adherence to the concept, I'd suggest that Psychic be paired with something else rather than it be a mono-type. Some people on IRC were talking about Bug to add a Stealth Rock weakness, but I worry about giving this Pokemon STAB options that are super effective against Dark types. After all, being scared of Dark types would be one of the main reasons to go with Psychic typing.
Last edited by Asylum_Rhapsody; Sep 18th, 2012 at 5:44:48 PM.
Reason: Forgot to mention the U-Turn weakness, then forgot about Psycho Boost