Dragon
Yeah, Ice and Ground attacks are common. I still feel, however, that a Poison/Dragon Pokemon would be able to succeed on a defensive/supportive front. Dragon still provides the most resistances, and thus, the biggest number of opportunities to switch in.
If we look at the actual top 25 Pokemon in usage...not all of the Pokemon that frequently carry Ice attacks are powerful enough to pose a real threat to a Pokemon that's not 4x weak to Ice. If our hypothetical Poison/Dragon Pokemon has 100/100/100/100/100/100 BST, running 252 HP EV's, the standard Blissey's Ice Beam does 32.67% - 38.37% - easily shrugged off with a recovery move. And that's the absolute worst that Blissey can do to it - any other attack is a pretty free switch (T-wave might cripple it if it actually does have 100 speed base, but that's something we'll worry about later). Gengar doesn't 2HKO with HP Ice unless it has Life Orb, in which case it just does 50-58% damage, which means it could be stalled out easily if you come in on any other move or invest in special defense more. And again, that's the worst that will happen. How it fares against standard Gyarados of course depends on Gyara's moveset - on bulky sets, Earthquake has a good chance of a 2HKO, versions with Ice Fang 3HKO normally and have a very shaky 2HKO after a DD (47.52% - 55.69%). LO gyara will generally win. Variants with Stone Edge/Waterfall and Restalk versions, on the other hand, will usually lose. That's 2 out of the top 5 used Pokemon that usually carry Ice/Ground attacks which our Poison/Dragon can stand against, and one which frequently doesn't carry the right type of attacks.
Of course, a lot of that is conjecture as we're nowhere near deciding on a stat spread yet, but you see my point - weaknesses to Ground and Ice don't automatically doom a utility Pokemon. Plenty of Pokemon with defensive or utility value like Jirachi, Celebi, Heatran, Gliscor, Roserade, etc have multiple common weaknesses but succeed regardless (if it seems like I'm grasping at straws for examples here, it's partially because the statement in the idea for this CAP is very true - there's a big lack of quality utility Pokemon out there). However, as you'll notice with many of Pokemon I listed, the biggest trend is having several valuable resistances - Poison/Dragon brings us much closer to this goal than any other type combination sans Poison/Steel does, which is a big reason that it deserves votes. Also, this:
TAY said:
This is exactly why I want to make it Poison/Dragon. It may function terribly against Garchomp and Bulky waters and Syclant, but it provides a great switch-in to Revenankh (!!!) and Pyroak, and any utility/wall pokemon in the game. I'm not concerned about making it weaker than the previous CaP's (though it's pretty unlikely that this will be unplayable), I just want something cool that serves a unique role in the metagame and changes the way the other CaP's are used.
Is a pretty good point I overlooked. Poison/Dragon makes for a great counter to Pyroak - resistance to both STABs, SE STAB of it's own, etc.