Ok I feel kind of stupid asking this question :D but how exactly do you get your pet to be able to do these "battles" somehow I'm not getting this whole concept haha. Thanks everyone :)
-Evie
Pets have to have at least 10 deployed levels before they can battle other pets or gladiators at the Coliseum. Once your pet has reached 10 levels and you've deployed them, then they'll appear in the drop-down box to battle pets when you're viewing other pets' pages or the Coliseum pages. You can level up your pet by entering it in the hourly contests. When your pet has gained a level, you can deploy it by going to that pet's info page, where you'll have the option to choose what stat you want to increase with that level.
oh thanks! That clears up a lot :)