I haven't played since pre-Epic but I also never got into wave dashing, even at the GC level. I rarely found my teammates using it or being bested because of it. Viable but overrated is where I landed on it.

Regarding the random air flips, I did find using that technique useful against opponents who excel at reading ball movement. I rarely needed it in team games, but sometimes in solo an odd hit that goes (relatively) in the direction I wanted is just enough to confuse them. Using it everytime though is just stunting.