This is just my personal opinion from the amount of Cammy I’ve played in SF4. I was reading on Gamefaqs a couple days ago that Cammy can’t do shit against Turtle players. I found that pretty untrue, so here’s what I had to say on the subject.
I think Cammy can do pretty well with turtle-style players. Against some Ryu turtlers i’ve played in SF4 online, what you do is when you have an EX slot, or whatever the fkn name is for it and you can predict a hadouken coming out, do an EX hooligan combination. Sails right over and grab 'em. If you do it right they’ll still be “frozen” in the hadouken stance when you hit, so they won’t have a chance to crouch.
And her EX spiral arrow, which, by the way, I think Cannon Drill was a much better name for it goes underneath projectiles. Against a turtling Ryu, I just spammed the EX SA, and nailed him every time he went for a fireball.
Cannon Spike is a relatively safe move if blocked. A good thing to do is to always do a LK CS, unless you KNOW you’ll connect with it, in which case do an EX or HK one.
Quick spin knuckle goes through projectiles, not sure about Ryu’s ultra, haven’t tried it yet and the Fierce Standing punch and Crouching Fierce are great snuffs.
That’s good for Ryu and Ken players, anyway.
As for the turtling Chun-Li players, the big problem is her standard attacks linking together. One hit with those and she’s chaining the attacks. Chun-li has a great poke game, from what I’ve seen. Against a chun-li player, you really gotta wait for that opening and strike. Force it if need be. But it’s hard to really bait a good Turtling Chun player, as they’ll be waiting for an opening as well.
In contining with the above point(s), I’d say a big thing to keep in mind with Cammy is corner pressure. Keep 'em pinned and they’re all yours. At least from what I’ve experienced. Her HPs and C. HK come out fast, so they’re great snuffs, or at least a good trade. But keep them pinned and just chip away. which I find she does fairly well.