Kelpstone

I managed to do this with two pets:

- Strand Crab (or any crab with less than 1800 HP): 1/2/2
- Ikky: 1/1/1

1.) Start with the crab and put down Whirlpool. Your crab will die in ~2 hits, don't worry about it.
2.) Bring out Ikky and cast Black Claw. On the next turn, cast Flock. Kelpstone should be dead soon after.

If you don't have Ikky, Zandalari Anklerender and Zandalari Kneebiter will both work. Just use Black Claw, then Hunting Party instead.

[npc=154918] phased out for me, while I had the quest What Will It Lure? in my log.
After turn in that quest and I returned to Kelpstone, he was visible for me.

i simply set up a team of lvl 1 aquatic pets (just a suggestion to keep it easy for people who are new to pet battles) - no special strategy, abilities or anything else needed.
winning regular lvl 25 fight against this guy can be a real challenge depending on how many pets you already have collected and which of them might be the right ones for this fight - but when you use a Lvl 1 team, he usually dies pretty fast 👻
just make sure that your pet's first attack does a reasonable amount of aquatic damage.
the winning pets will get a good amount of xp after the fight and eventually level up (speaking of a lvl 1 team).
so it might be a good idea to find a nice team of easy-to-get pets, gather some clones of pet number 3 and simply replace it with a fresh lvl 1, to make sure your enemy doesn't unlock it's next ability --> ❗this is the case as soon as one of your team is level 2 or higher❗ this way you're able to maintain 'easy-mode'.
pet number 3 is usually the only survivor... but if you're lucky and the enemy is almost down while your pets nr. 1 or 2 are still alive, punch him until only one or two attacks are needed to kill him. then start using the 'pass' button to let him kill all pets that were involved in the fight and therefore qualify for XP. finish him with pet nr. 3. always put the cheapest / weakest pet in slot nr. 3, this way you only have to find a replacement for one easy-to-get-pet 😛
💡- works for any level-scaling pet battle, just chose the right type of pet / dmg / resistance for each fight -💡