Against Kratos, Raiden, and Nariko, it pays to play defensively. You want to make sure not to get caught in their combos. Block and dodge should become your best friends. I main Sir Dan, and I find that one of his most useful combos is down square (air), square, square, up square, up square, up square (air). Also, you want to be constantly using side circle (walking skull move). If it doesn't catch them, it will force them to either jump or block, so you can more easily predict where they will go. Neutral square is great at mid range. Get them in the air and use Dan's level 2. It will usually work.
You could use your down circle on top of them, since a lot of Nariko's combo's make here up close with an enemy for a while. Your down circle move gets you about 5 AP per second. Also use your over and circle a lot, and your triangle. Go for attacks where you don't have to go up close, until you see the right opportunites.
For Kratos you should try to dodge a lot, and maybe use your over and circle to make him fall, and if you're fast enough you could get in a combo.
And with Raiden, it really shouldn't be that big of a problem, I play Sir Dan quite a bit on Quick matches, beat a lot of Raidens, try to dodge him when he's about to go in for an attack, and when you get the opportunity strike him with a hit or combo.
Heck, a lot of the time people get annoyed when fighting me because I can be a "slippery target" So they go and try attacking everyone else.
Sir Dan has excellent block abilities, and usually, I'm not saying everyone, but a lot of players who choose Raiden or Kratos are button mashing spammers. Pulling out your sheild, blocking and dodging should be your main focus. If they go in for a grab, (Not very often usually, mind you), Dan's moves hit very hard, and you can knock them away after a good dodge if they come close enough.
-Using side circle and nutral triangle are good for getting them moving.
-His down circle move is good for when someone is stuck in a combo, or unavailable to move somehow.
-When you have your sheild out, your charge gives you more AP and knocks through multiple people. Although when you don't have your sheild out, you deliver a short knockback, and get some distance to set up for a combo. I guess you could choose what you want to do from there.