Which pets can actually be spawned by an Orca? Well, unsurprisingly the list has changed a lot over the years...
Orcaelogy
When Star pack was first released onto the test server, Orca had a different ability. It summoned 2 faint pets at every level, however those pets would be level 1, 2 and 3 depending on the level of the orca. This was super strong and wouldn't last, but interestingly we can also see from this later cowpigcow test server footage that Whale was actually a possible spawn for a while!
Panda and Swordfish seemed like they might be possibilities too since their abilities involve fainting, however I don't believe they were ever included even during the test phase.
Golden Age
The arrival of Golden pack heralded a new age for the Orca, with a whopping 17 new faint pets it could potentially spawn. Top tier fainters like Nyala and Wolf were now on the menu, but so too were duds like Pied Tamarin and Vaquita. Golden also introduced the first token pet with its own faint ability: the Smaller Slug. Unsurprisingly, and maybe disappointingly for some, this pet has never been in the list of valid spawns.
Recent Past
So which pets ARE in the list? Well, the revamp of Puppy pack shook things up again, removing the reworked Armadillo but adding new faint abilities for Mole, Chicken and Lionfish as well as 8 brand new fainters. Here are all the pre-Unicorn possibilities...
Modern Era
But even with an already massive list of potential summons, Unicorn pack was about to arrive to inflate the spawn pool even further. With almost 100 new units including tokens, the pack would end up adding 15 new faints in total...
The Future
The current tally sits at 65 - over an entire pack's worth of faint pets. But even now more adopted Orca children are being put through their paces on the test server. At time of writing Cockroach, Kiwi, Firefly, Bass, Fairy Armadillo, Tuna, Tarantula Hawk and Ammonite are all sporting faint abilities. It's anyone's guess if there will 'only' be 8 more when the updated Star pack goes live...