I think some posts and typings are neglecting the fact that Ninetails its outclassed and outmatched by many things in OU and thats its saving grace is its ability, Drought. Sun teams are essentially planing with five pokemon due to Ninetails uselessness. To rectify this CAP-5 needs to have typing that pairs well with the weakness of the fire type–specifically rock and water as presented by the most commonly used weather starters in Tyranitar and Politoed.
To effectively check Tyranitar CAP-5 should be a Fighting
type. This type could easily switch into Tyranitar's dual STAB with little consequence, playing offensively forcing the Tyranitar to switch thus applying pressure on the sand team lest it wants to loose the weather war. Offensively and defensively I feel that fighting types provide the best check against sand, specifically where Tyranitar is the sand starter. The fighting type also adds a stealth rock resistance which is valuable to a sun team, reducing the penalty of switching CAP-5 in and out.
As for dealing with rain there are two types that should be taken into consideration when pairing them with the fighting type. These types being Electric
, the former being an offensive check to rain team while the latter is a more defensive check.
The Electric type although makes it harder for CAP-5 to switch into water moves it can effectively check common pokemon found on rain teams with its strong Electric STAB. Its similar to the fighting type when checking sand on this regard. The electric typing also gives CAP-5 a neutrality to Hurricane, though uncommon this neutrality should enable to the pokemon to take a hit (if necessary) and damage (if not, knock out) the threat at present. The electric type however give CAP-5 a weakness to Earthquake/Earth Power, moves commonly found on sand teams forcing out CAP-5, forfeiting offensive momentum something the electric typing aims to gain. This also compounds the weakness of ground moves that sun teams usually have.
The Grass type is very much an opposite to the electric type despite their common purpose, defeating water types. Grass typing allows CAP-5 to switch into water moves and immediately threaten the opponent out for previously stated reasons. The grass typing is also more useful when confronting sand teams, allowing CAP-5 to check Tyranitar and Hippowdon (something the fighting type cannot do). A virtue of being a grass type is the innate resistance of ground moves–this fact is especially important on a sun team where that weakness may be common between team members. The weaknesses brought by the grass type are many, specifically to Ice Beam and Hurricane. The former being on present on all water types and the latter being present on niche but powerful pokemon (i.e Tornadus-I)–there is little CAP-5 could do against Hurricane, however on a sun team the switch-in to an ice move should be plentiful.
I support both dual typings of Grass/Fight
, my preference is for the Grass/Fight type as it checks rain and sand better defensively. This typing also promotes superior synergy between CAP-5 and Ninetails, its weather starter. CAP-5's resistance to Rock, Ground and Water and in turn Ninetails resistance to Ice proves this to some extent. If CAP-5 were to have Rapid Spin (or support moves of similar merit) the support CAP-5 would give to a Sun team would be invaluable.
I am hesitant to support anything weak to fighting
due to the ubiquitous presence of powerful fighting types, Terrakion and Keldo being stand outs among them due to their affiliation with weather and/or outright strength. Their strong STAB moves often spell out disaster for sun teams and a CAP-5 that is weak to fighting would not help this problem.