At certain locations on the world map you'll encounter random battles with Friendly monsters. You'll know they're friendly when the music changes to a distinctly "friendlier" tune. When you encounter them they'll ask for a gem or ore. If you give it to them they'll reward you with a lot of AP and an item. You can encounter them in any order except for the Friendly Yan. You must encounter every other friendly monster before he will appear. Also, sometimes the monsters will give you hints or even the item needed for the other friendly monsters.

Aside from the items and AP there's an extra incentive to finding all the friendly monsters. If you find them all you can use physical attacks against Ozma, a particularly nasty optional boss. Check out the Ozma Guide to learn how to where and how to defeat this boss.

Here are all the friendly monsters, their locations, and what you need to give them: