How to Fix PetBattle Teams for 6.1
stargrace 
If like me, you were sad to see that PetBattle Teams was no longer working after 6.1 deployed yesterday (and this is an AddOn that I highly recommend if you’re into pet battles at all) you can find a fix here:
To fix this for 6.1:
1. Open Interface\AddOns\PetBattleTeams\modules\GUI\GUI.lua
2. Search and replace (ctrl+f or search/replace with your text editor) every “Blizzard_PetJournal” with “Blizzard_Collections”
There are 5 of them in the file. Make sure “Blizzard_Collections” is capitalized like that and that the _ is an underscore and not a hyphen.