yonda
Jumping in rpg's is a bit different then platforms. I'm assuming their either using custom controls or 8 directional movement for their rpg. Also last time I checked, mario rpg for snes was isometric, so its a bit different then your generic rpg movement.
seba182
What I did for the jumping in my isometric rpg was have a player that has both 8 directional movement and platform behavior.
So when jump button is pressed, player disables 8 directional movement, enables platform,then Player vector Y-300. Then when player gets back to its original spot I disable platform behavior and enable 8 directional movement.
At the moment that's all I can hint at you.
Also one thing to note; an rpg might not be the best game to start off with. Try making some smaller games, then move up to an rpg.