(1) low poke (d.3) his teleport on reaction - hard to do online
(2) jump, and if you do close dive kick while he is teleporting, it will auto-correct and hit him
(3) keep a close Ice Bomb on screen as much as possible, and stand right on it or slightly in front of it
Basically, you have to have no hesitation and you have to read your opponent. If he teleports as you're inputting the motion for Ice Ball or something, you are just screwed and you'll eat a combo, there's nothing you can do. Raiden is not impossible to deal with, although it may seem so in a laggy environment.