Oh also, I really think the Electric-type might be worth looking into here. I haven't seen any really convincing posts yet, but I think Electric typing as the attacking STAB with something else for the defensive might be really nice. Electric / Poison compounds the Ground-type weakness (Don't pray for Levitate), but is a bit interesting. Some discussion there might be worth having!
Surely.
This CAP gives us a lot of different directions in which to go, but if we're looking for a Pokemon that has a mix of an offensive typing and a defensive typing, I think we should look no further than
Poison / Electric.
Now, some of the first reactions to this might be in the ballpark of "But DarkSlay, that's 4x weak to Ground! Whatever shall we do?". That's true, it's 4x weak to a Ground move. However,
is that really a bad thing in this metagame? Heatran is probably our best example of what happens with 4x Ground weak Pokemon, and Heatran has even more weaknesses than Poison / Electric does. Yet, weaknesses allow for good team synergy, and something like a 4x weakness is one of the best ways to force your opponent to react. I agree with Dusk in saying that you shouldn't rely on Levitate getting through either. I think this CAP can definitely benefit from a limited number, but highly concentrated, weaknesses, much like Heatran can.
Now, onto why this is a good typing. I'll tackle the typing individually, starting with the offensive based
Electric. Electric typing is a very good offensive STAB to have. It hits Water and Flying types super effectively, a relatively short but important list. Grass, Electric, and Dragon types resist it, while Ground is immune to it. That's also a relatively short list, with Grass (especially), Electric, and Dragon actually being covered with the other STAB move (if anyone actually cares to use it). It has a good amount of high powered attacks that can be Sketched, but not to the extent of V-Create or Sacred Fire. Examples would be Volt Tackle, Bolt Strike, Fusion Bolt, and others. It's generally a neutral offensive typing, striking down 13 of the 17 types for neutral or greater damage. At the same time, it doesn't boast a lot of type resistances to the STAB, making it a safe offensive option. Definitely a boon for this concept.
On the defensive side, we have
Poison. It doesn't hit much offensively, so don't mind that. Defensively, though, it resists some pretty potent types, including Fighting, Grass, and Bug (as well as Poison). It is only weak to Ground and Psychic. A few key resistances and a few key weaknesses. Fighting type resistance is really nice especially, as is a nice U-Turn resistance to prevent scouting (coupled with a Volt Turn resistance when combined with Electric). Electric also adds Flying and Steel resistances, which is nice. Don't forget the
immunity to Toxic and absorption of TSpikes. That's pretty neat if we want CAP to have an offensively bulky build.
I think this typing is
perfect for this project. It provides us with critical resistances, critical weaknesses, and a good, semi-neutral coverage scheme for a good offensively bulky Pokemon.
Other ideas I can support are
Poison / Grass (still don't think it's inferior to Ghost/Grass for many reasons including that Dark weakness)
, Poison / Dragon, and slight nods to
Electric / Psychic and
Ghost / Grass. Really don't like being Dark weak personally, though.
EDIT: Really, really liking the idea of
Grass / Electric. Very few downsides, and actually combined brings two somewhat neutral offensive types together to form a decent defensive unit. I might support this over Poison / Electric, but both are very viable.