I've been thinking about it more and watching this discussion and the discussion on #cap, and I'm going to narrow down my personal convictions to Steel and Water.
I don't think that Fighting brings enough key resistances, and I suspect that it's there mostly for the STAB and for retaining the Fighting resistance. The problem with trying to retain the Fighting resistance at this point is that many Fighting-types have coverage moves to hit Flying-types. Scrafty carries Ice Punch, and Mienshao I think carries Ice Punch, too, if anyone still cares about that dude. Virizion commonly carries HP Ice. CAP 1 would even be weak to itself! I also don't like Poison because it seems inferior to Fighting for the purposes of this concept.
Steel helps CAP 1 by neutralizing the Ice weakness as well as the Rock weakness, so that it doesn't immediately keel over to these threats without significant bulk. It also resists Dragon as a bonus. Blaziken would probably win against either typing, anyway. Additionally, the so-called "coverage issues" are kind of a dumb argument. CAP 1 could still *use* Fighting-type moves or Ground-type moves or whatever, and we could also give it a support movepool. Flying's a great STAB by itself, anyway. Steel also allows CAP 1 to resist Return and doubly resist X-Scissor (both from Excadrill).
I still find Water a good alternative. Water can at least make Landorus and Excadrill wary of switching in, which ties into the "choke point" theme going around. The typing's weaknesses are also very appealing, as Electric attacks aren't all that common from Pokémon other than Rotom-W/Thundurus/Raikou (and the former two will probably counter this CAP regardless), but if there's a spike in Electric users due to CAP 1, that will play to the team's favour. Water also neutralizes the Ice weakness for better prospects against the Fighting-types mentioned earlier, though the Rock weakness still hurts here.
Last edited by capefeather; Mar 8th, 2011 at 6:58:05 PM.