So I've noticed that a lot of the training that goes on, whether for EVs or exp, goes on in a set few places. Might be interesting to implement hidden bonuses (or negative effects) to training in less-used places/hard to get to areas, as an easter egg of sorts. Bonuses could be along the lines of:
-Invisible (or not) Healing Circle in areas like the jetty by the mew truck
-Small exp/ev bonuses - not 50% or anything, but like 10-20% more exp or double evs for training in something like MT. Moon B2F
-Rare Spawns - rare pokemon have a tiny chance (.01% or somethin) of appearing in weird areas. For example, a hoppip spawning in the grass above power plant
-Special Area Effects - the area affects pokes in ways beneficial to some, detrimental to others. Something like a constant "Gravity" effect might be kinda funny, or water/mud sport active
-Gradual poison/healing areas - by standing in these your pokes would either slowly lose hp or slowly gain it, respectively, unless they were poison type... someplaces like the Mt. Moon tunnels seems like it should have this, what with all the paras
-Drowning - whirlpools can suck you in while surfing and send you to the nearest pc