S. Attack: 110
S. Defense: 59
Alright, I want to outline a few things before I delve into the full explanation. My primary focus on this spread was the speed stat: 104. I believe this is the best possible speed for making Weak Armor, and CaP4 in general viable. 104 speed outspeeds Genesect, the pixis, Hydreigon, and other notable threats. It is undersped by Infernape, Terrakion, and Tornados-T. At 104 speed, CaP4 can outspeed many of the Pokemon it would naturally prey upon, allowing it to do its job. However, it still must have the speed boost from weak armor to bypass its three main speedy checks from the major weathers. Additionally, at +1 it can outspeed Scarf Genesect. I hold that if it cannot do this, then it will be unable to sweep in a BW2 metagame where scarf Genesect alone would reach into the top fifteen OU. Thus, it is naturally fast enough to do what it needs to do. But, only at +1 can it outspeed a few crucial checks that would normally revenge it midsweep. This makes Weak Amour viable, without making the other two abilities useless.
My second consideration were the offenses. I put 110 Special Attack into it to ensure that 252 Neutral Special Attack with a Life Orb could always OHKO Terrakion. But it is also there to max out the Pokemon's special attack that it can legally have with 104 speed. If this Pokemon can not hit hard enough to score crucial KO's, there will be no use for Weak Armor. At -1 Defense against a Pokemon that has a physical attack, relying on further setup is a huge liability. While 110 without a spammable stab move is still fairly middling for a sweeper, I believe that it must hit hard to make Weak Armor useful. What's the point of outspeeding if you can't KO?
105 attack was selected next, as it can ensure a 2HKO on standard Chansey after Stealth Rock with no EV's and a Close Combat. While this may seem like an odd calculation, consider that this Pokemon is designed to be counterless. While some people will shout "Psyshock!" a timid CaP4 with a Life Orb and 130 Special Attack fails to earn the 2HKO on standard Chansey. In order to keep the Pokemon counterless, it needs a way to deal with the blobs, so 105 attack was selected. It was later changed to 107 for the purposes of creating an even 585 BST.
Special Defense was designed to be fairly frail, but capable of taking some neutral hits. 110 HP was selected as a generic high HP number and a place to start from. 59 Special defense ensures that it will always by OHKO'd by Offensive Heatran Flamethrower in the rain after Stealth Rock, which works out to a 100 Base Attack power neutral STAB hit from a base 130 Special Attack offensive build. Realistically, a "specially frail" Pokemon probably shouldn't be able to do this, and this seemed like a good benchmark to start from.
95 Defense was selected to tank a non-switch Pursuit from Scizor with 4 HP EV's 100% of the time after Stealth Rock. It can take a round of Life Orb recoil and a Pursuit and Stealth Rocks with 252 HP EV's. This prevents LO sets from setting up on Scizor that are locked into Pursuit, or Scizor that mispredict. However, sets without Life Orb can still do this, and particularly bulky sets can still KO Scizor and then possibly another Pokemon. In regards to Weak Armor, CaP4 can tank a Scizor Pursuit as long as it doesn't have Weak Armor and, provided Scizor is indeed CB, proceed to sweep. 95 defense isn't the crux of this set, but it adds an interesting dynamic.
104 speed is critical for keeping Illusion and No Guard viable while making Weak Armor relevant. Offensive stats allow for max power/key KO's that allow for Weak Armor to sweep and make it "counterless" with the right coverage, and defenses limit what it can tank on the special side and keep a physical bulk that has an interesting dynamic with Scizor.
Back. Back in full May 15th. Please don't issue new gym challenges until that point.