Combat is turn-based and there is no time limit on each round in a PVE Pet Battle. You can take your time to determine which spell to use next. Some pet abilities have multiple round cooldowns, while others can do extra damage if certain conditions are met. Be creative and have fun testing which combination of attacks works best against different wild pets!
Learned this today: posted a comment, came back later to see if there was any feedback, reloaded the page: the page posted a copy of my comment. That was not what I wanted. I just wanted to check if my comment was posted and if there were some responses. I did not want to post a copy of my comment from 5 hours ago. And, a humble guess, I think the majority of the users are not expecting such behavior either.