Well seeing as they brought it back in Gen. IV, I really hope that they will include the night and day feature once again. This really brought the games to life for me and made everything so more realistic. Also, I wouldn't mind at all if the Dive feature from R/S/E was brought back, like others have said. It isn't necessary, but I think it just adds that extra thing to do and enables you to capture more Pokemon and explore some more too n_n And definitely the return of Gym Leader rematches as well. Also wouldn't mind seeing Contests spread out around the region like they were in R/S/E. ^^;