How it works:
The weekly event is pet battling so you get 200% experience for all of your pets. Today there's a daily that is easy to solo with a single pet so you can effectively level 2 pets from 1-25 in 9 battles (about 10 minutes of time).
Level 110 Character with World Quests unlocked
Level 25 Iron Starlette Battle Pet (Abilities: Wind Up, Toxic Smoke, Explode)
Optional: Safari Hat & Pet Treat
1) Fly to Valdisdall, Stormheim and go to the world quest "Beasts of Burden"
2) If you have it, use your Safari hat for 10% bonus and use a 50% bonus pet treat
3) Set your Iron Starlette as the primary pet and add your two leveling pets underneath
4) Use the following abilities: Toxic Smoke, Wind Up, Toxic Smoke, Wind Up, Explode
5) Watch as your two level pets climb in levels and use a bandage to revive your Iron Starlette
6) Repeat 9 times and your two level pets will be 25, replace them with new level 1 pets and start over
Alternate Strategy if you don't have an Iron Starlette. Takes a bit longer to do sadly and you can only level 1 pet at a time.
Requires Level 25 Lil Bling
1) Start with Leveling Pet and use one ability
2) Switch to Lil Bling
3) Cast Extra Plating, Make It Rain, Inflation
4) If you're alive after Inflation is finished cast Make It Rain/Inflation until you die
5) Finish him off with whatever 3rd pet you have