Some pets have innate strengths and weaknesses (Much like pokemon).... so here they are! All percentages represent resistance if it does not say WEAKNESS
Blumaroo - 10% Air
Bruce - 20% Water
Buzz - 20% Air
Chomby - 20% Physical, 10% Fire
Cybunny - 20% Earth
Draik - 10% Earth, 10% Fire
Elephante - 20% Physical
Eyrie - 20% Air
Grarrl - 20% Physical
Grundo - 30% Dark
Ixi - 30% Earth, 20% Dark WEAKNESS
JubJub - 20% Physical, 30% Air, 20% Fire WEAKNESS
Kau - 10% Air, 10% Earth, 10% Fire, 10% Light, 10% Physical, 10% Water
Korbat - 30% Dark, 30% Light WEAKNESS
Nimmo - 20% Water
Peophin - 20% Water, 10% Earth, 15% Fire WEAKNESS
Poogle - 10% Earth, 10% Fire
Pteri - 40% Air
Scorchio - 10% Earth, 30% Fire, 10% Air
Shoyru - 20% Fire
Skeith - 10% Earth, 10% Fire, 10% Physical
Tonu - 15% Physical
Tuskaninny - 20% Water
usul - 20% Dark, 10% Fire WEAKNESS, 10% Water WEAKNESS