NO LONGER FOLLOW WHAT THE IN GAME BUTTONS OR FAQS ANSWERS SAY
Ok now that I have your attention, to complete thr Raijin throw combo with minimum stress and frustration please follow me and think outside of the box.
It took me a good 3 hours, couple mountain dews, and a lot of my music playing for me to do this.
Now I'm not saying the other answers are wrong but this works I know. It took me a while to finally try different things then the answers were saying but finally i did and it worked!
So here is my way of doing the Raijin Throw Combo.....
1) When the opponent is standing to the left of you rotate the left thumbstick as fast as you can (hopefully quite fast) counter clockwise and after 2 or 3 rotations start tapping A maybe.... 3 or 4 times as you keep rotating the thumbstick and he WILL do the 1st step to the combo which is throwing the opponent up in the air. (When the opponent is standing to the right rotate the thumbstick clock wise. So whichever way he is standing you want the thumbstick to be rotating to where it is coming down on his head.) This then becomes not an issue of "will he do it" but an issue of "when he will do it." Now you maybe not do it the first time but give it a good go and youll get it.
2) For this one you must have good reflexes for when he does it. Though if you master the 1st step as I did you should have the hang of when he will do it. NOW this step is also a bit tricky and you MUST be quick. See what i figured out was that if you simply tap A once it will not go in, it wont be acknowledged. So you must quickly try to do the arrow combo and hit A 2, 3, or 4 times... however many until he does it.
Now IF you have mastered the first step and done the second one one or two times like I have right now you will be smiling like theres no tommorow :> A. for the fact that you havent done the damn grapple that puts you behind the oppent for some time, and becasue "Man I almost did it there!!!!"
YES!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! JUST NOW DURING WRITING THIS VERY FAQ ANSWER HAVE DONE THE RAIJIN THROW COMBO!!!!!!!!!!!!!!!!!!! I LOVE IT!!!!!!!!!!!!
3) *Exhale* Sorry I am beside myself right now OK!. For the third step all you have to do is when he is kicking the opponent in the air is do the arrow combo as sloppily as you want and hit A a couple of times and you should have it. Thats all I did! And I only did the 2nd step 3 times!