-Gives it a better shot against Skarmory and Forretress, two common users of Field Effects, without having Ground's five weaknesses, and without Poison's problem of finding some way of dealing with them without any STAB moves (which for it would be even more annoying should we end up going Physical, since Skarmory and Forretress have high Defense).
Both of which could easily be resolved by giving Poison a Fire type move, and a passable Special Attack Stat. Also, Fighting is only going to do more to Skarmory when it Roosts. Otherwise, it will just laugh at your attacks. (Assuming pure STAB here, since only Poison's STAB's keep being brought up.)
-Still gives us a shot against Blissey, another common spammer of Status, should we actually end up making this thing more of a Special-attacker.
Blissey doesn't like
any strong Physical Attack. As a matter of fact, Tyranitar can severely cripple it with STAB Pursuit, which our CAP Pokemon now has access too. We're talking about typing right now. Movepools and Stats will be strongly reflected by what types we choose. I seriously doubt that if Poison or Ground make it through, the entire community is going to leave them both wide open to Blissey. Why can't they both get Brick Break? Pretty much any Pokemon with arms gets it already.
IN other words, it allows us to actually deal with the Pokemon that are spamming secondary-effect moves, without having a buttload of weaknesses (Ground) or having a poor offensive-typing combination.
Again, a Pokemon's movepool is not simply limited to it's STAB moves. A great OU example of this is none other than the offensive powerhouse itself, Salamence. When was the last time you saw a Salamence with a STAB Flying move? I can honestly say I never have. That's because Flying gives it an extremely useful immunity (Ground), but offers nothing really in terms of attack. It still does well however. Why? Because it can use Earthquake, Flamethrower, etc. That only reinforces my point behind Poison. It gives excellent resistances, an immunity, but you will most likely never attack with it.
Fighting may not actually give it any Status immunities, but there's still the Ability for that, so it's not too much of a problem.
So your whole arguement for a type that can't really stop any secondary moves is, "We'll fix that with the Ability"?
Whereas if we don't make sure we can actually switch in on them should we mispredict and they actually use an attack (Ground's problem), and actually be able to do something to them once we come in (Poison's problem; yeah, you'll be able to switch in on Toxics, but what after that? What's it going to be doing once in?), the status-immunities aren't going to really be meaning much comparatively. As a result, Fighting seems to have the best balance of pros and cons to me, and that's why I'm supporting.
So, Poison is absolutely worthless once it switches in? I didn't realize that an entire type could do absolutely nothing outside of absorbing Toxic Spikes and Toxic status. Surely you aren't implying that Poison, once switching in on a mispredict, is utterly helpless. I can also safely assume that this CAP is going to be relatively bulky. It would not serve the Concept well at all if it ended up fainting after a hit or two.
In summary: Not every aspect of the CAP can be built around stopping some secondary-effect.
Of course not. It will be foolhardy to even attempt that. However, that does not mean it should have no immunities at all, and in the end putting
all the pressure solely on the ability.
Edit: As for the possibility of a Poison-type getting Stuff like Flamethrower, that's still relying on it's stat-build, which we can't be sure of yet. If it ends up getting a Special Attack of something like 40, even those won't help too much. Thus, I don't want to rely on that possibility too much right now, as I can't be sure that those attacks will actually be something that will work at this stage.
And I should just assume that Dark/Fighting will automatically be able to function as well? What if it ends up with something like a 70 in Attack? Then how is it going to reliably threaten anything, STAB or not? Yes, I know that is an extreme example, and very unlikely to happen due to the fact that is was chosen as Dark for Pursuit. However, I was merely providing an example, with significant evidence to back it up. Assuming only goes so far for both parties. Until the actual movepool and stats threads come out, anything other than "This type offers this. This type offers this." is really a moot point, imo. (And I can be guilty of poll jumping easily as well.)