Evolution helps increase the GR of the pet but in order for that the pet has to be evolved in the right place. For each element there is a different place to evolve it at. The following are as follows:
Sky City (21, 11)
Measure Stage (31, 22)
Bandit Cave Entry (22, 22)
Water City (51, 53)
Casting Flowery Rains also helps to boost up GRs. Pet Raising Gods/Devils get an increase of GR when evolving pets. Some pets cannot be evolved by non pet raisings. Pet Raising Gods/Devils may be needed to evolve some pets but pet raising points will be lost according to what pet it is.
Composing is the combining of two pets to increase the GR of one pet. The pet must have 100 loyalty in order for it to be composed and also over level 500. Composion Areas are also important. If the pet is composed in the wrong area then the GR may possibly decrease instead of increasing. Composion Areas are as follows:
Water City (51,53)
Measure Stage (31,22)
Bandit Cave Entry (22,22)
Also Pet Raising God/Devil bonuses can be added when composing.