Switching between many characters and controllers,How to switch between many character controllers and sprites

I'm very VERY new to unity and c# as a whole, making a 2D platformer where the player is constantly evolving into new monsters with different sprites and controllers. There's 14 monsters total, so obviously a lot of controllers.

Right now i have a Player(GameObject) as a parent to all of the different monster characters, which each have their own controller scripts and sprites. The Player has a script i want to use to handle the the swapping of monsters.

I want to change the Monsters simply by setting one of the character objects to active, and the others to not active, but i have no clue how to reference gameobjects in c#, i also want to make sure there isnt a much easier way of doing this.