Yea... need to be like 130 or 140+ to catch but can only use them if you are lvl 90+ sadly. Before that I use the Calcutta Cows. They are so cute and colourful. Even had my Fire using one with a -200 weights. I got it to lvl 54 or 59 before it was accidently dismissed -.-. (wanted it to be her pet. named it CowCow. a play on word for Emperor Cao Cao from The Three Kingdoms, same pronunciation.)

ANIWAYS~
The higher the pet the more STR they have and they harder they hit, which contributes more to your DAMAGE and more damage means more EXP.

So I have a Alt logged out in Calcutta pasture. and another logged out at relic when I need new pets I just log them in to catch. Trade/sell in carnie and team goes back to bursting.