As soon as you start seeing him teleport behind you, start a hit confirm combo (I always like using 2,2). It does require just a little bit of reading your opponent / figuring out his pattern as to when he likes to teleport. Most of the time, he will be hit by the hit confirm because most Raiden's like to attack the second that they materialize from their teleport.
this is gonna sound controversial and I might get a big fat slap from some of the guys here .... but works for me.
let him superman you to the corner! more often than not i end up on the winning side, if he tries teleport out i always back jump and he ends up back in the corner and eating a meaty jip combo coming out of his teleport.
also a good idea, to keep a clone behind you. even if he supermans he eats the clone and you get a free combo.
Has anyone noticed this cross over jump input bug that happens specially against Raiden? Every time he teleports and I read it I try to cross over to start a combo with jip but my input simply bug and every time I drop the combo for no reason, even doing it with perfection.
If you're in front of your ice clone Raiden can't teleport and Sub's 2,2 > Raiden's soul in a head on fight. Don't clone on him after a knockdown combo either, wake-up invincibility on Superman will tear through the clone every time.
d4 also stuffs anything he can do with his strings besides f2,4. Basically dare him to do something when you have a clone up. This is the ONLY matchup I sneak an exClone in. Raiden rage is timing the normal clone... teleporting, and landing right in to the exClone.