From the PTR notes, we know that Fluxfire Feline is getting his Wind-Up taken away, and he'll no longer be one-shotting everything in sight. But the ability that's set to replace Wind-Up is actually pretty interesting. It's called Flux and you can check out the ptr fluxfire on wowdb
Flux deals 12 base damage to the frontline pet and 9 base damage to the backline, for a total of 30 base damage and an ATK ratio of 1.5. So we have exactly the same issue of stacking multipliers that old Fluxfire had: you can combine Supercharge or Prowl with an ability with an intrinsically high ATK ratio. In this case, let's look at a breed 8 Fluxfire (322 power):
Flux deals 12+(12/20)(322) = 205 damage to the frontline, and 9+(9/20)(322) = 154 damage to the backline
and now let's add Prowl, to get 2.5*205 = 513 damage to the frontline, and 2.5*154 = 385 damage to the backline.
Old Fluxfire could do ~1800 damage in 3 turns. New Fluxfire can do ~1200 damage in 2 turns, but it's spread out between all of the opponent's pets. It's not quite as convenient, but it's still a ton of damage, and I bet we can build a team around it. It also has one nice advantage: even if the frontline pet dodges the Flux, the backline pets will still take damage.
The team would probably look something like this: Fluxfire, Fluxfire, Brilliant Kaliri. The first two pets are there to blast as much AoE damage as possible, and the last pet is a fast hard hitter that can kill low health opponents before they can retaliate. In hypothetical other games this last pet might be called a 'sweeper': it could be a Kaliri/Owl, a Moth, Enchanted Broom, Peddlefeet, a breed 5 Nether Faerie Dragon, a breed 5 Flayer, etc.
A hypothetical turn sequence:
Fluxfire1 -- Prowl, Flux, swap out
Fluxfire2 -- Prowl, Flux, Claw/Pounce until dead
Fluxfire1 -- If near death, Flux; otherwise Prowl, Flux, Claw/Pounce until dead
At this point, assuming each Fluxfire lives for 3 turns, you've put out 1575 damage to their frontline pet and 884 to their backline. If each Fluxfire can live for 4 turns, you've put out 2227 damage to their frontline pet and 1095 damage to their backline. Now your sweeper steps in and faces 2 or possibly 3 pets that should have fairly low health, and uses its speed advantage plus cooldowns to kill them--for example Kaliri can use Predatory Strike to kill a <650 health pet before it can take an action.
This team is a bit gimmicky, but it puts out a ton of damage, and unless you can kill the Fluxfires in 2 turns, there is really only one ability that can prevent your backrow from taking 700+ damage in 5 turns. That ability is Sandstorm, which cuts Flux damage roughly by half. Unfortunately, Anubisath Idol is everywhere and will only be stronger in 5.2, so he represents a major obstacle for this team (and AoE strategies in general). Nonetheless, I think this has some real potential to be a fun comp to play with.