Hello!
This is really obvious if you've been playing pet battles for a while, but i thought i would share it anyway.
If you queue up with one or two level 1 pets, and one high level (10+), you will be queued with people who are much lower level than you. This allows you to very easily stomp their pets with your higher level pet.
For example, when i queue up with two level 1 pets and one level 12, i mostly get opponents with pets in the range of 4-8.
If you have a pet with any sort of heal, you will outheal their damage without problem and two-hit most of them.
TL;DR:
1. Queue up with two level 1 pets and one high level pet. (Or two high level and one level 1)
2. Get queued with easy opponents.
3. Win.
I hope this helps someone