I use bair waveland extremely liberally, you get your best use VS fox and falco who fall down from bair at 55% ish, and wont hit the tech. Proceed to fireball reset -> grab, or bair waveland -> turnaround utilt their missed tech.
Works great on FoD, as our bair will make them land on the lower platforms, and we can bair waveland into a utilt. Grab to follow up, or fsmash.
Works really well on sheik before knockdown percent - you bair and waveland away, she thinks she can hit you in time but can't. CC her dash attack follow up/whiff for a free grab..
As for landing it, dash in, pivot shield so you're facing backwards is one way. It's a truly fundamental technique for mario and you need to have it down from all momentums, with all states of aerial drift, and be able to WD either direction, with the perfect waveland.
Bair is totally reaction punishable by half the cast though... so in this new meta we can't use it VS good foxes, falcons, or marths. Works amazing on shiek though, as a wall, and a bait, a combo starter before and after knockdown %s.