how to play as other cats when Battling!!

[lavendercloud]

I'm new to playing the game and I am a bit unsure of how to use the cats I've recruited to battle. Do I have to make the first move or is there something I'm missing. I haven't tried anything else because I don't want to be wrong.

[Sirius]

If you mean you can't find a way to add them to your party, that can be done at the Moonstone