List of pets.
Getting the best out of your pets.
For min-maxing stats: In later stages where all pets have passive bonuses (pet level <100, but in this case usually applies to levels 30-99), selecting the pet with a lower level passive bonus will usually yield a stronger boost. (If two pets have active boosts of a and b, with a passive boost x and y that is less than 1, the higher of x or y will provide a stronger boost. Therefore the pet with the weaker boost is usually selected as the active pet). If both pets are at the same tier of passive bonus, select the pet with a higher level.
Pets eventually start to become your main source of damage around stage 550, however, depending on your artifacts, this could be more or less depending on artifacts.