Pokemon is said to be based off DQ's use of monster companions in DQV which was released in 1992, but the concept of Monster companions and building a party of them actually started with Megami Tensei on the Famicom in the late 80s. So really its just a giant conga line of people borrowing and re-using the idea.

The more you know and knowing is half the battle...G.I. JOE!!!