It depends on the mon you're talking about. Stone edge on Hawlucha or banded Tapu Bulu to hit Zapdos is kinda situational. Stone edge on landorus is not situational at all, it's one of his best coverage moves.
Protect on many mons can be considered as situational in single, since it could always be useful to scout choiced mons, but lacks utility outside of that.
Haze is maybe one of the best examples of it. It's really situational, or even garbage, on many Pokemons that get it, except on pex, which almost always use haze.
Last example, calm mind on suicune is always useful, calm mind on volcarona to counter oricorio is one of the most situational things imaginable.
If you want to figure out if a move is situational on a Pokemon or not, it's pretty simple: ask yourself, will this move find a use against most of opposing strategies? If not, it's probably a situational move.