Cait Sith is a fortune teller with who gives unreliable readings. He rides on top of his huge stuffed Mog and invents many wacky attacks. You'll meet this person in the Gold Saucer.
I really don't like Cait Sith at all. I don't like the person he is, he attcks with a megaphone, I don't know how else to classify him except as stupid. When it comes to fighting though, he is actually a pretty good fighter. His physical attacks are strong, and his limit breaks can be pretty devastating. He only has two of them and they are unpredictable. His first one involves several dice, which he throws onto the ground and the result determines how much damage is done to a single enemy. For his second limit break he plays a slot machine and the outcome determines the attack. Almost all of the outcomes benefit you, except for death to all, but that's very rare. Since he has no Ultimate Limit Break, you only have to find his Ultimate Weapon, HP shout. Just go back into Shinra HQ during your second raid on Midgar. Then go to the 64th floor and search the lockers and you'll find it. I didn't use him much because I just didn't like him. If you decide to use him, he's a front row fighter. He's good with Materia, but don't put too much on him. I personally would keep a him a physical fighter. If you don't hate him, he can be a pretty good character to have on your team.