Single player is fun if you like to play survival crafting games alone. “Pokémon with guns” is not actually a very good description. It’s a monster capturing game, and the creatures are cartoony like Pokémon, but it’s a third person survival crafting game. No turn based elements or choosing monster move sets or anything like that.
It’s more like Ark with Pokémon instead of dinosaurs
I’ve got to recommend Monster Hunter Freedom Unite. One of the most legendary games in the series for its sheer amount of content. It might feel a bit dated if you’ve played World or Rise, but still good