isperia: 1. Makes a pet attacking enemy at the first round instead of last round, the pet is not gain experience when he dies fighting powerful enemy and it will not gain experience to when my character kill the enemy first.
2. Give a pet some abilities or characteristic a player can give with gold or credit and maybe adding more pet too. That will make them worth raising.
3. Dreamer, you can make a PVP just for pet (tournament maybe) or just include them in PVP battles.

That's what I can think for now. Aside from number 2 and 3, number 1 is the most important.