Doesn't seem like it'd be too hard to do. You could make a second hitdef for specific instances of laying on the ground, or make a custom hitstate.
I'd imagine the custom hitstate would be more reliable.
So you'd want some type of code in your hitdef(s) of any combo that can send P2 into the position. You could use P2Stateno in the hitdef, or targetstate. Targetstate is probably the best bet because you could use a var to keep track of exactly what puts P2 into the situation.
Ok thanks for the Suggestions, I also want tailspins to hit in midair only once , for example while the opponent is in midair a roundhouse from p1 will send P2 to "tailspin" state and if another roundhouse will hit p2 while he's in a "tailspin" state it won't send p2 to tailspin state again
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