The CPU on hardest difficulty appears weak to wakeup moves and anti-airs, particularly characters such as T-Hawk and Chun Li. Guile’s or Vega’s flash kicks are great to have for this, a wakeup Shoryuken also works wonders. The computer’s weak against air attacks after they’ve fallen down, as well. So, as Vega, for instance, you can usually Barcelona Attack them with impunity as they wakeup. They will offer the occasional counter, but the computer isn’t actually programmed to learn from its mistakes, so it will invariably fall into the same pattern. As Dhalsim, you can poke Gief (and others) from afar, and he will simply walk into it all match long until you get the win. I agree, though, jchensor, every time I’m good against A.I. for a long stretch of time, my online vs. skills go the way of the buffalo temporarily. Best to avoid it altogether.
P.S. Nice Immortal avatar, leaveal. \m/