>>57686014Standard, which what is legal are the most recent sets, a few letters at the bottom indicate it, you can use the Pokemon TCG Live game to test out stuff since it is pretty generous and gives a ton of meta-relevant decks
There are a ton of cards that are basically always reprinted and always useful but a few are worth it to just buy singles rather than hunt for them in packs
Incirneroar currently has no meta relevant decks but you can use a site search for his legal cards, their cost and try to make something work, if you want to build a mill deck Great Tusk mill is the most successful one right now but it is not really that good, really simple though so it's a good start