"Second, let me point out that the Physical/Special Bias does not only aply to attack, but also to defense. You want this CAP that can come into Latias/Rotom/Celebi, but you want to nerf its Sp.Def by giving it a Physical build?"
No. As I pointed out in my original post, I want this pokemon to have a good physical attack but also a good s.def. I was not aware that the two are mutually exclusive.
"Also, everyone keeps saying that this isn't a wall breaker, but the majority of secondary users are walls, and if they aren't walls, they're Trick users. So what about being a wall breaker that punishes Trick users isn't stopping the secondary?"
Not to poll jump, but if we wanted CAP9 to be a wall-breaker, we would have given it a more offensive bias. You'll note that Infernape and Salamence, two of the premier OU wallbreakers, are in the "Offensive" category, while ours is in the "Somewhat Offensive" category. That does not preclude our CAP from being a wallbreaker, obviously, but its stats are not entirely suited to being one. A bulkier spread seems more appropriate.
More relevantly, a bulkier spread would allow our CAP to have a much easier time stopping the secondary. For instance, Infernape is not at all comfortable switching into some secondary users it could otherwise demolish (Skarmory does absurd damage with Brave Bird, Swampert kills with EQ, Vaporeon kills with Surf, Bronzong kills with EQ, etc). This allows them to use their secondaries because you know that if you mispredict and they attack instead of using a support move, you just lost a pokemon for nothing. If our CAP is bulky, however, it doesn't care what a secondary user does, and therefore would have much more freedom switching in. It no longer unduly fears random grass attacks from Celebi or the newly OU roserade. It no longer fears the omnipresent ice beam from walls. It doesn't fear Rotom-C's leaf storm. If we try and make our CAP into a wallbreaker, it cannot risk switching into these attacks, and so will always be limited in achieving its primary goal.