Genshin Impact style team selection

So I have a system in my project to be able to switch characters that was relatively easy to set up but I am finding it harder to find a basic tutorial in regards to a solo player game team selection system. I really like how Genshin Impact gives a player the ability to choose 4 characters from their list of playable characters and the ability to switch them at any time. Does anyone know of a good way to do this?