Coming back to Poke'mon after a long time away, is this normal?

[Praetor]

I was running around and encountered a Boldore. I have one in my party that I've been leveling up since it was a little Roggenrola. My Boldore is level 37. The Boldore I encountered was lower level and kept using Power Gem. Now I don't remember my Boldore having the chance to learn Power Gem at all. Is wild poke'mon knowing moves they can't learn from level up normal? Is it new with Gen VII?

Further, can anyone help me understand the attack list here? Specifically, the Ultra Sun/Moon list for Boldore that says it can learn Power Gem via evolving. I always assumed that the list of moves without a level next to them were the default movesets of the poke'mon when encountered in the wild but I don't think I've ever seen a wild poke'mon with a move that none of it's stages can learn by level up. Also, if the earliest Roggenrola can evolve is 25, why does Boldore have moves listed for levels 4-23?

 

[BCVM22]

Moves with a — listed next to them are moves that the Pokémon can learn via the Move Relearner. Most Pokémon have them chiefly so that you can add them or re-add them to the move set as you tinker, while some Pokémon have moves that can only be learned via the Move Relearner.

A wild Pokémon will generally have the last four moves in its learnset relative to its level, i.e. a wild Lv. 40 Pokémon will have whatever four moves it learns up to and including Lv. 40.