Over the weekend I made the tough call of permanently dismissing three old pets. I picked up a water strider for combo spell power / crit buff. I picked up a wind serpent for its debuff . And finally, a hyena for the attack speed buff. I also swapped out a creepy Halloween spider for a neon spider I got as part of a rare quest. This fills out many of the buffs my 10man raid often doesn't have.
Sadly - and I mean sadly - I had to get rid of three pets. Yes, I picked the ones I haven't used in the longest time but it still felt bad. I'm not sure how to abandon any other pets. It seems cruel.
I was glad I didn't seem to need to pick up a pet that can do a battle rez. But this was a mistake. Wowhead has it as a brez with 60% health and 20% mana. I was reading Petopia who had it at 20% health and 0% mana... which would be really terrible.