We've already confirmed many of the new pets that were released with 4.3, but Blizzard has announced three more upcoming pets in their official guide to the 4.3 pets and mounts page! [source]
- Lump of Coal - Reward from Stolen Present during Winter Veil
- Lunar Lantern (Alliance) - Sold by Valadar Starsong for 50 Coins of Ancestry during Lunar Festival
- Festival Lantern (Horde) - Sold by Valadar Starsong for 50 Coins of Ancestry during Lunar Festival
Both the lantern companions are Bind on Use, so with the help of the Neutral Auction House, it's likely that a single character will be able to acquire and learn both pets regardless of their faction.
The Stolen Present is a reward from the new level 80 Feast of Winter Veil daily quest, You're a Mean One... This may indicate that Lumpy will not have a 100% droprate from the Stolen Present, but players will be able to try their luck once per day during the Feast of Winter Veil. The Feast of Winter Veil is coming up soon, so we won't have to wait too long to find out!
There are a few pets that were not mentioned on the official Blizzard guide on Patch 4.3 companions. These pets include:
- Gregarious Grell - Common loot card from the upcoming TCG expansion deck, Crown of Heaven
- Sand Scarab - Common loot card from the upcoming TCG expansion deck, Tomb of the Forgotten
- Sea Pony - Fished up from the coasts of the Darkmoon Island during the Darkmoon Faire monthly event
- Soul of the Aspects - Unknown
Both the TCG vanity pets were discovered as redeemable options from Landro Longshot on the 4.3 PTR, and the Sea Pony was a confirmed fishing companion on the PTR as well. Keep in mind that while these pets were datamined and confirmed on the PTR, there is no guarantee that they will be available.
The source of the Soul of the Aspects is still a mystery. For now, we will have to wait to find out more about this mystical pet. Hopefully we won't have to wait too long for news about it!