Super Smash Bros. GameCube Adapter for Wii U/Switch
Nintendo had released an Adapter that converts a regular GameCube controler into a second Controler that lets you play on the Nintendo Switch without paying for another JoyCon.. the bonus side of buying this is that it lets you play Super Smash Bro's 5 with a GameCube controler which is ideal because where all used to playing Super Smash Bro's Melee & Brawl with it even the Pro's will agree.
The other great side is you don't need more Joycon's to play multiplayer in alot of games that are single & Multiplayer. their are in fact a few games that wont work with the GameCube controler but if you play like Kirby Star Allies 2-4 players it works perfectly fine or if you like the feel of the GameCube controler better you can play Mario Odyssey that works well.
I would recommend getting this but would inform you to look more into it.