"Green" is Leaf in my hack. She has the original black outfit and choses the starter superior to yours. "Gary" is the champion and helps you out from time to time. he's the one that gives you the rainbow/silver wing to catch ho-oh / lugia to fight Silver. so, Gary is not your rival. Instead, you have the two heroines from the pokemon adventure series: the other being Yellow, who chooses the starter weak to yours.
Due to map hacking not being fully available, i cant put the Sevii islands into the game
But, after beating the Elite four, you have a new expansion of wild pokemon to catch.
Maybe some fakemon.