Flow

Head to the World Quest Flood Warning objective at 64.09, 82.76 in The Forbidden Reach. Flow must be defeated in its Rare quality form to reward the Water Storm Essence, which teaches the Flow pet.

Flow can appear at Legendary, Epic, or Rare quality. Defeating two or three Storm-Touched Ohunas in the small area around Flow at 64.09, 82.76 will reduce its quality down toward Rare. This weakening is temporary and will expire, requiring you to re-defeat the Storm-Touched Ohunas. Other players in the area benefit from this weakening as well, so if Flow is already weakened to Rare when you arrive, you can battle it immediately.

One reliable team uses Mini Mindslayer (Life Exchange, Amplify Magic, Mana Surge) as the lead, followed by two filler level 25 pets. Open with Life Exchange on cooldown, then Amplify Magic, then Mana Surge. When Mini Mindslayer dies, bring in a backup pet to finish the fight.

Blood Boil is a straightforward alternative and is available on the Auction House. Use ability 3 whenever available, then ability 2 whenever available, then ability 1 when both are on cooldown, cycling in the pattern 3, 2, 1, 1.

Ikky (Black Claw, Flock, Savage Talon) paired with a Zandalari Kneebiter or Zandalari Anklerender can defeat Rare Flow without pre-weakening it via Storm-Touched Ohunas. Open with Black Claw, then Flock with Ikky. When Ikky dies, swap to the Zandalari pet and use Black Claw, then Hunting Party or Leap.

If you need to weaken Flow first, the Storm-Touched Ohunas nearby at 64.09, 82.76 can be handled with a Sprite Darter Hatchling, which can nearly solo them using Arcane Blast and Life Exchange when health is low. A second Nether Faerie Dragon can be brought as a backup.