Lurking in the Shadows in World of Warcraft is a pet battle World Quest located in Ardenweald.
There are a few strategies to defeat Grixis Tinypop and his Nightfang in a friendly game of pet battling.
By far the most popular strategy to deal with Nightfang is to go in with a level 25 Iron Starlette. Using wind-up, supercharge, then wind-up once more for massive damage, you will one shot Nightfang from using these three moves in that order with your Iron Starlette.
Lurking in the Shadows WoW: How to Complete the Quest
Iron Starlette is fairly easy to get, requiring you to complete a chain quest in The Blasted Lands, located at the Shattered Landing. Considering you will be max level, this chain should take little time.
If you don't have the Starlette, and don't care to do the quest chain to get it, pet battles scale down to your pet's current level in Shadowlands. Realistically, all the level 1 pets you haven't used can just be thrown in to try and fight Nightfang, and the boss will scale down respectively to your pet level.
Happy pet battling out there!