Adding my own pvp hot takes:
Zanj’ir Poker / Kelpfin / Murgle / Necrofin Tadpole: Real shame that Uncertainty and Inner Vision can’t overlap: Having a superpowered Punch/Fish Slap would be a fun and gimmicky, albeit useless combo. The good news is that it gets Inner Vision and Whirlpool, allowing for some pretty nasty setups. As it stands, it seems that Clobber may be strictly reserved for faster breeds, whereas X - Inner Vision - Whirpool will be the default.
Pearlescent/Lustrous/Brilliant Glimmershells, Caverndark Nightmare, Chitterspine Devourer, Lightless Ambusher, Chitterspine Needler, Glittering Diamondshell, Sandclaw Nestseeker - Basically the same as the already-available Freshwater Pincher. The movepools and stat bases are getting more diverse for this group, right?
Chitterspine Deepstalker - This pet looks like it could put out some nasty damage with Prowl + Dive/Whirlpool. Skitter also gives it some possible leverage against Undead pets. Combine that with a nasty base attack, and this pet could do a number against stall teams. Only problem I have is that its speed is a bit high for a Prowl pet. On the flip side, that means that Dive could be used primarily defensively, while Prowl could just be combined with Skitter. We’ll see.
Chitterspine Skitterling: This pet gets Black Claw and Swarm. I will repeat that. THIS PET GET BLACK CLAW AND ALSO SWARM. This pet basically an Aquatic version of Ikky, even down to the base stats. While this may be incredibly predictable in a pvp setting, I expect this pet to get a lot of usage in PvE battles. Only drawback is that Pinch isn’t the best move for a first slot, so you may just have to rely on raw Critter damage.
Hissing Chitterspine - On Live, the lion’s share of pets with Hiss are either Snakes or Beetles/Roaches. This will be the first Aquatic pet to get access to the move, which has solid synergy with Dive, in addition to doing fairly good damage in general. Unfortunately, Pinch’s damage ramp-up does this pet no favors, as it has a fairly low base health. So you may have to lean back on Skitter. Again.
Spawn of Nalaada - This pet is a carbon copy of Abyssal Eel, which I suppose is good news for Horde players that can’t be bothered to farm paragon caches on Alliance. The movepool isn’t the most thrilling to me.
Abyssal Slitherling - I’m not a fan of Deep Bite, given this pet’s middling health. Squeeze gives it some decent compensation for its below-average speed, but it doesn’t have any abilities that can really manipulate a speed advantage. Overall a mid-tier at best pet.
Skittering Eel - Just another Spawn of G’nathus, which should be an easy drop to get at this point. This shouldn’t have much extra value in comparison, although Spawn isn’t a bad Aquatic pet.
Mindlost Bloodfrenzy/Daggertooth Frenzy - Both of these pets are carbon copies: Okay health and attack, pretty good speed. Both movesets are unfortunately quite generic, so they’re no better than the abundance of Aquatic pets out there already. Oh the flip side, they’re just a remake of the relatively hard-to-get White Carp, which may be a relief to the more casual collector.
Bloodseeker - Bloodfang WOULD be nice to have, had it not been for the fact that taking it would result in all 3 abilities having fairly long cooldowns. As such, it can’t really be relied upon by itself, it needs some external support to work well. What’s worse, without it, it becomes a pretty generic Aquatic pet. It doesn’t even have anything to make Blood in the Water always hit.
Deeptide Fingerling - See Bloodseeker, but replace “Bloodfang” with “Huge Fang”.
The good news is that Huge Fang has a much shorter cooldown, so you’ll run into fewer no-attack situations.
Nameless Octopede - Literally Inky, and Inky is pretty cheap nowadays. So meh.
Amethyst Softshell / Prismatic Softshell / Wriggler / Damplight Slug - Literally just the Snail family. Suppose it may be useful for pet dungeon snail strats.
Blackchasm Crawler - Weather attacks are always a welcome sight, although Darkness has counter-synergy with Absorb. Slime - Goo - Darkness seems like a pretty good Anubisath Idol counter, so there’s that. Probably preferable in pvp to generic snails, because of mentioned weather.
Spireshell Snail - This snail’s speed is almost average… Almost. Move-wise, Slime isn’t bad, nor is Shell Armor. I’m still more intrigued by the Blackchasm Crawler, though.
Muck Slug - This pet has some pretty nasty damage potential with Goo + Slime + Quicksand. Unfortunately, the latter move means that this slug’s relatively impressive base speed will basically be pointless. The generic stat spread would have worked much better.
Trench Slug - While I can’t say I’m a fan of getting rid of Shell Armor for Spiked Skin, having Ooze Touch over Absorb makes this pet a better choice than Blackchasm.
Seafury / Stormwrath - Literally Hydrath Droplet, which are fairly cheap. Movepool isn’t anything to write home about.
Sandkeep - Just a Living Sandling remake. They’re cheap, grab one instead if you want to cash in on their pretty decent movepool.
Scalebrood Hydra - Literally a Hydraling, which is super easy to get.
Brinestone Algan / Budding Algan - Odds are both of these pets will have fairly different breeds from the otherwise-identical Amalgam of Destruction, which isn’t the easiest pet in the world to get unless you’re willing to part with decent money or have friends willing to lend you pets. That doesn’t work in the favor of these pets, as it’s a movepool that works well with the P/P breed that the Amalgam has.
Coral Lashling - Literally a Carnivorous Lasher, so getting this pet may end up saving a few pet charms if you just want the moveset. It gets pretty decent survivability thanks to Leech Seed + Feed, but it’s nothing to write home about.
Golden Snorf / Mustyfur Snooter / Snowsoft Nibbler - Interestingly, these are just Beast versions of Dig Rats, which aren’t terribly easy to get to begin with. Comeback can be pretty good with the Beast racial, but plenty of beasts have it already.
Duskytooth Snooter - Having two speed-based abilities in one slot with a slightly-above-average speed isn’t something I’m a fan of. The fact that just about every ability benefits in some way from a high speed doesn’t help things either. Might be decent with speed support, but pretty bad otherwise.
Rustyroot Snooter - This pet is a bit slower, but is thankfully less reliant on speed, with Buried Treasure and Scratch as options. Slightly stronger than Duskytooth, IMO, but that isn’t saying much.
Sandclaw Pincher - This pet boasts both a weather move and a rooting move, which can mess with weather synergy-dependent teams, but that’s about where the good ends. Pinch is generic, Triple Snap is awful, Frost Shock is basically pointless, and the stat line is bad.
Sandclaw Sunshell - This is the superior Sandclaw. It has a slightly better stat spread, the same weather and root benefits, and a stronger alternate first-slot move in Frost Spit. This pet may actually be almost decent.
Great Sea Albatross - For some weird reason, this pet, of all things, will be making Metabolic Boost no longer a Zergling signature ability. Does a flying pet even need a speed-booster? Not really, particularly considering its base speed is already pretty good. Outside of the weird choice in speed boosting ability, this bird brings nothing interesting to the table.