Depends. You can only have one "If" in a order, not two:
"If Blazer uses Fire Punch, Protect from it and follow with a Hyper Voice! If not, Psyshock"
Is illegal. Now, if you do this:
Psyshock! If he uses Fire Punch, Protect instead, and follow with a Hyper Voice" Is legal.
And you cannot:
"If he uses X, go for a A + B! If Z, use Y instead followed by X! " Is so illegal. You can only change one of your order (Use X and Y), too, not both.
If still in doubt, ask a LO, as it's hard to explain. But just avoid using two "if" and never do something like "If he does Z, switch X to Y and Z to B.