For leveling with wild pet battles, I like going near the beasts of fable spawns. Lots of wild pets, respawn quickly, no travel, all are lvl 24-25. Also a good way to farm stones.
Only so many tamers to fight in one day now, and could be hard with only 3 lvl 25's to choose from. So until you get a few more to 25, I think this would be your best bet.
I put in a pet with Decoy (like DM Zepp), then a lvl 1, then back to Zepp who is good against beasts. This works until the pet is about lvl 8-10. Then it can take a hit and go first, so the fights go faster. A pet just has to make it one round to get exp. A lot of wild pets have a defensive ability also. So until you get a few more up there, a lvl 1 might get lucky and the pet just casts a shield or something.
Try to lvl up pets from different families to maximize your team's strengths. GL and have fun