Pokemon is an easy as fuck game series. You can beat any Pokémon game with any Pokémon, even Sunkern, with the proper knowledge and the use of the correct moves, items, and strategies.
Are some Pokémon easier to do this with than others? Of course. However, the point still stands that any Pokémon can be used to beat the game.
If you like a Pokémon, use it. Don’t worry if it’s suboptimal, or if it’s not “”””””competitively viable””””””, just use what you want to use.

There’s no such thing as a shitmon