[SDPhantom]

I'd honestly convert it to a loop.

function BattleDex.RecordBattle()
    if not C_PetBattles.IsWildBattle() then return; end
 
    local primary=0;
    for i=1,C_PetBattles.GetNumPets(2) do
        local species=C_PetBattles.GetPetSpeciesID(2,i);
        BattleDex.RecordPet(
            species
            ,C_PetBattles.GetLevel(2,i)
            ,C_PetBattles.GetBreedQuality(2,i)
            ,primary--  Passes zero for the first iteration
        );
        if i==1 then primary=species; end-- Sets the primary species for following iterations
    end
end