Pyra Nair I feel is pretty underrated. In the right situations it kills earlier than up air and it's fucking huge. Also comes out pretty quickly for a Pyra move

For overrated I feel like I have to go with her Side B, Blazing End. Yeah it's a pain to deal with online I understand that, but it's really not that practical outside of tech chase scenarios and ledge trapping. But even then, if you got the read F-Smash is even better than Side B -> footstool. Good players will almost always dodge and punish it

I guess I could do Mythra as well, most underrated move is probably Ray of Punishment/Chroma Dust, for a character that can't go very far offstage because of their average, linear recovery, making her susceptible to reversal, this move is really useful at keeping people in edge guard situations. It's also a fantastic oos option because of how big its initial hitbox is, but it's a more known use I think

Most overrated move is Foresight. Kidding, it's also Side B, Photon Edge. This move is only good online where it's unreactable, otherwise even in situations where you could use it, unless your opponent is at a very specific "not quite kill percent, but also not really combo percent", you're better off going for a combo, even a small one. Besides killing with Mythra with raw attacks isn't the best idea