Fjord Worg Pup or Stitched Pup
I find these pets stronger than Chrominius.
Both the Moth and Ragnaros are good ideas.
Do you mind to upgrade pets or catch the same pets with different breeds?
You seem happy with your Unborn Val'Kyr. I assume that you want to build a PvP team around this pet.
You are in luck. The Unborn Val'Kyr is a strong pet that can do well! It will go well with a lot of pets. Some ability combinations work really well together with Curse of Doom, Haunt and Unholy Ascension.
Potential synergy with Unborn Val'Kyr:
Fast pets that can control the opponent (Dodge/Stun/Clobber/Blinding Poison/Decoy)
Pet that increase the damage of Haunt/Curse of Doom (Howl/Stampede/Corrosion)
Pets with strong heals (Consume Corpse/Wish)
You can, of course, pair the Val'Kyr with any strong pet. Synergy with other pets make the Val'Kyr shine in my opinion.
Ideas:
Unborn Val'Kyr (Attack / Curse Of doom / Haunt) + speedy Death Adder Hatchling (Poison, Blinding Poison, Puncture Wound) + Arctic Hare (Flurry / Dodge / Burrow) or Moth (Attack / Cocoon / Dust) or Emperor Crab (Surge / Shield/ Healing Wave)
You do not own a Death Adder Hatchling, but this pet has strong synergy with the Val'Kyr through its avoidance and speed. You basically avoid a lot of attack, while Haunt does its damage.
Unborn Val'Kyr + Arctic Hare (Flurry / Dodge / Burrow) + Lil Bad Wolf (Claw+Dodge+Howl)/ Deathy (Attack / Call Darkness / Stun)
The idea behind this team is similar to the heal team (below), it however does not have heals. It rather uses avoidance to get maximum efficiency from haunt. You use Haunt (+ optional Curse of Doom) and swap in the most favorable match-up. Arctic Hare is a super fast pet that can dodge for 3 turns in a row while haunt ticks. Lil Bad Wolf can use its avoidance for two rounds AND buff the damage from Haunt+Curse of Doom by 100%.
You can use Deathy as a replacement for Lil Bad Wolf, to have a better chance versus healing/aquatic teams.
Note. Deathy has 289 speed, which is mediocre. Its stun only works when you are faster. Lil bad Wolf would be better overall, but both teams can work.
You can replace these avoidance pet with other pets that have avoidance + decent speed.
Unborn Val'Kyr (Attack / Curse Of doom / Haunt) + Singing Sunflower (Solar Beam / Photosynthesis/ Sunlight) + Magical Crawdad (Attack / Shield / Wish)
This is a very slow team. You basically slowly stall your enemies to dead. A match usually goes: (optional Curse of Doom) Haunt -> Photosynthesis -> Sunlight -> Swap Crawdad -> (optional attack) Wish. All three team members must stay alive for as long as possible.
As you have noticed, Haunt is really strong. This team kills pets through Haunt, while the Singing Sunflower and Magical Crawdad survive.
There will be teams that will be a stalemate. It will take some time for you how to play this team, the wins an hour will be quite low even when you win a lot. You might find the playstyle very boring, it however is a decent team.
Note. When I replace the Unborn Val'Kyr with another pet that has Photosynthesis it becomes a very useful team for the Celestial Tournament. It is terribly slow, but it has killed 4 trainers for me (it might be able to kill more).
Unborn Val'Kyr + Stitched Pup (Bite / Howl / Consume Corpse) or Blighthawk (Bite / Consume Corpse / Lift-Off) + Moth (Attack / Cocoon / Dust)
You can use consume every Haunt! This makes the Blighthawk a very durable pet with avoidance (Lift Off). You can add a strong Flyer to counter the aquatics.
Unborn Val'Kyr + Blighthawk (Bite / Consume Corpse / Cyclone) + Lurky (Punch / Lucky Dance / Stun)
This team is build around two setups. Unborn Val'Kyr has synergy with Consume Corpse and Clobber (when Lurky is faster). Cyclone has synergy with Lucky Dance. This will be a difficult team to pull off. It isn't that strong, but it has a Murloc!
Unborn Val'Kyr (Attack/Curse of Doom, Unholy Ascension), Toothy (Rip, Surge, Blood in the Water), Infested Bear Cub (Undead attack, Stun, Maul)
Buffed damage from Ascension, combined with two pets that work really well together (Rip/Blood in the Water/Maul).
These are just a few random suggestions. I am not sure if these teams will work for you. I have not tested the Murloc teams, but they seem fun!
Note: Emperor Crab/Spirebound Crab will counter around 20% of the teams by itself.
Twilight Fiendling (h/h)
I never used this pet. I'm intersted in getting one. How do you use it? ^^