Alot of people out there are having trouble leveling pets, but its not so hard.
Requirments:
Fast water with good HP/SP
Team that combos (may nees weights depending on level or all non comboing teammates use suport skills and pets atk)
Bellychain necklace (u get in holly (wlogamers on youtube have a guide for that :) ))
First step:train the pets in kelan cave, or forest behind kelan untill lvl 10-13.
Then put the bellychain necklace on you pets (each pet needs one cus raises 250+HP!)
And train at forest untill lvl 23-30. Ur choice but the higher the easier :P trust me.
(make sure u have lost of food and water needs e.rem btw, just so pet wont die)
Then once you are lvl 30 with your team training at tender cirrus will be helpfull.
Train there (WARNING:i am not fully sure what lvl they are in pine forest plz leave it in the comments below!) untill u reach 40-45.
Now u need 4 boats, of any veichle that can go on water (Ex. Space craft, jalor, etc.)
Then make your way to oslya and go to the raptors. You should be atleast lvl 40 to train here and with a good team aswell.
While training here u will pick up some meet ( use for food!)
Train here from 50-55
Now i am sorry to say but i cant finish this guide. If u think u know places to go after comment below please :) and if u wanna stay at oslya longer u can its not hard to train u will get atleast 100exp untill 2x the. Should be around 200.
I have heard training at South pole from 60-80 is helpfull but i havnt tried it. Gl