My gymnasts remove their lip rings, ear rings, and tape over industrials. Tattoos are a no no... We even go so far as to remove tongue rings when we catch them.
It's a safety thing as well as an aestetic thing. You may just want to wait until after highschool, since you should be in season now. Or just wait until this season is over so you can let it heal enough to remove it as necessary.
Or.. IMO.. just dont do it at all. I think they're icky.
High school gymnastics here is pretty strict about that stuff, even more than USAG. Although I don't know how USAG would feel about lip piercings either. I would advise you to wait on it regardless of how the competitive rules handle it if you're doing gymnastics though, at least until the off season. Think about how often your face brushes mats, your hands, your grips, catches on your upper arms, etc. I have nothing against piercings but you won't be doing gymnastics forever. I'd just wait a little longer.
yeah, i had my first highschool meet yesterday. (i didn't do well at all. haha) and i had to take out my earrings which i never had to do with USAG. and my ears are gauged so i really hate taking them out. but you can't tell they're gauged unless you're looking for it. and i have a tattoo but it's covered by my leo even without shorts. (like on my hip is where it's at)