114 HP / 110 Atk / 100 Def / 100 SpA / 65 SpD / 101 Spe
PT: 192.3438 (Excellent)
ST: 128.4700 (Good)
PS: 193.2127 (Excellent)
SS: 177.4455 (Excellent)
BSR: 390.8751 (Excellent)
Things to consider:
Speed: 252+ hits 331, speed-tying Landorus-I and notably beating Jirachi, Lucario, Rotom-W, Hydreigon, Haxorus, Mamoswine, Dragonite and Heatran. 101 ensures that at +1 (WA boost) CAP 4 can't be revenged by Scarf Genesect, something I wanted to avoid, and that Scarf Landorus-I was not a 100% revenge. At +1 CAP 4 hits 496, comfortably outrunning all unboosted OU. As someone else said, it is important for CAP 4 to be able to do something with a Weak Armor boost. I felt that 101 was an ideal speed to maximize the reward of Weak Armor.
Lets consider the case of a CAP 4 at +1 Spe, -1 Def from Weak Armor. How hard is it to revenge?
As you can see, with WA CAP 4 has a certain set of revenge killers. However, with No Guard, different pokemon deal well with it. Let's use a CAP 4 252+ Atk and LO.
These Pokemon are pretty comfortable dealing with a Physical hard hitting CAP 4. The reason I gave CAP 4 100 base SpA is to expand its options. With No Guard it becomes quite easy to abuse the common high powered special attacks such as Focus Blast. 100 base SpA allows this to be an option for CAP 4, without being the only good option or being too overpowering. In this way I see a versatility to CAP 4 akin to Salamence. Salamence had a number of incredibly threatening sets like DDance, MixMence, SpecsMence, and others. Salamence's good mixed offenses allow it to perform well at a number of roles.
I expect that the versatility of CAP 4 will play a huge part in determining how successful it is. Ideally it should be able to do well at many different things, each role being defeated by different counters and checks. I hope that my spread can accomplish this to the fullest.