this happened to me, jsut replace pikachu's thunder with marth's counter:
3) Reverse Thunder
a) Jump left or right in the air, then do Thunder
b) Quickly tap the opposite direction (do a half-circle with your control stick) to change the momentum of Pikachu, which makes him go in the opposite direction of where he was going, but the Thunder will still land in the area at which you first entered the command to do Thunder.
c) Uses: Mind games, Spacing, Edge guarding (run towards the ledge/off of the ledge, then do a reverse thunder to return safely to the stage)
it's like a momentum change during the move
but with pikachu it's easily done, with marth I can't seem to recreate it for some reason
what did I do exactly?
So what you're saying is, you can B-Reverse Pikachu's Thunder and then safely return but..
1) You can't B-Reverse Marth's counter
2) You can't return safely after doing this
3) Both
Answer:
1) I'm not even sure if Marth can B-Reverse his counter, there's no real point to it anyways.
2) Pikachu's Thunder slows him down considerably and totally stops his momentum. Marth's Counter just throws his momentum off and send him downward
3) Combine the above answers
If I misunderstood please correct me, I apologize.
EDIT: With Marth, it's better anyways to do a drop down counter or ledgedrop counter. For example, if a DK is recovering low, you can drop down and counter his recovery.