I made a deck centering around tera steel skeledirge, is is it any good?

Instead of Nemona, I'd suggest having Iono, because that lets you see more cards in the early game and disrupt your opponent in the late game.

You should also have support Pokémon that can help you draw cards, such as Fezandipiti ex. You may also want to include Arven so you get the Items you need at the right time.

I can see how this deck is supposed to work in theory, but I have a feeling that you may end up with a bad starting hand more often than not. And if you're missing even one piece of this deck, whether the Stadium, Infernape, Skeledirge, etc. you may have a tough time taking on decks with consistent draw and quick setup.

The best way to test the deck is, of course, via TCG Live to see how it stacks up against popular decks you're bound to run into. Use that to experiment. No energy at the right time? Consider Earthen Vessel. Bad starting hand? Try Squawkabilly ex.

Hope this helps!