Well I don't have a link to a 3DGS tutorial that is about this exact topic but the basic problem you have to solve shouldn't be that difficult if you have done some other basic tutorials. I'd suggest you start making a character walk on a terrain first. Then you should worry about the random battles and how you want to do them as there should be several ways to do that and how you do this is up to you. You for example could save the player's position on the map and then load another level (would have some loadtimes though) for the battle and when it's finished you'll load the world map level again and put the player at the saved position...
You also could try a more advanced approach and that is trying to have it all "streaming" - i.e. a fluid switch between combat and world map where you'd have to use some tricks to accomplish that. I unfortunately can't give you a more concrete help as I didn't use 3DGS for quite a while but after having done some basic tutorials you probably can finish that solution with switching via loading another level...
Thanks Toast very helpful, I am working on a ff7 game I am currently re making some maps from the first to see if i have the brain to do this lol. Thanks from Kyle
