Lemme just say that the term "Oppo," or opposite, can only apply to bartwists, barspins, and scooterflips.
You bartwist, barspin, or do scooterflips naturally with one hand, and then if you learn how to do them with the other hand then it is an "Opposite" bartwist, barspin, or scooterflip.
Those are the only instances where it is acceptable (mildly) to call a trick opposite.
You can only spin frontside or backside and you can only tailwhip or heelwhip. You cannot opposite tailwhip or opposite spin. It is ignorant to think of a heelwhip or a frontside spin as opposite.