The thing about moonwalking is that, outside of a few characters that have good moonwalks, it doesn't really help. It's a "mindgame" tech, that relies on tricking your opponent. To my knowledge, outside of Falcon, I don't think there are setups that require moonwalking in order to be effective.
What moonwalk is good for, aka has a totally legit use:
Grabbing the ledge quickly while facing towards the ledge (with applicable characters)
Boosting your momentum for off-stage edge guarding (with applicable characters)
All of the other uses are gimmicks at best, and honestly only Falcon can really make something of it in a real way.
Unless the two things I mention are something your character gains from, moonwalking isn't something that gives you anything terribly beneficial. It doesn't give you more options, as it suffers from all the same limitations that dashing/running has. It's tricky, and it can trip someone up, but that can also backfire in your face. It's cool as hell, so lots of people learn it for that, but you are better off actually working on micro-spacing with wavedashes.*
* Controlled wavedash lengths that allow you to move the space you need without over-extending while keeping your options open.