Again this is just an idea for what information you could provide. If you have more you wish to put or less, feel free. This is just to help out.
Name:
Age:
Species: (i.e monkey, dog, tiger...)
How was the pet obtained: (i.e it is a ninja summoning:describe how you came about to be able to summon this animal, adopted, found in the street...)
Owned by/Loyal to:
Personality:
History:
If Ninja animal you may wish to provide information on;
Skills:
Weapons: