>>20708324Uh, Crystal was pretty significantly different. Game was different, Battle Tower, Eucine/Suicine plot, move tutors, updated dungeons, and some other stuff I'm forgetting.
Oh, and Crystal was the first game that let you play as a chick. G/S didn't have that option.
Yellow was pretty significantly different from R/B/G as well (Pikachu follow, starters given to you, James/Jessie/Meowth, completely updated sprites, updated dungeons, and updated NPCs.
Highly unlikely there's going to be an Emerald. Especially when X/Y haven't gotten their 3rd/sequel/whatever yet.