I'd like to see the opposite gender PC play a role as a rival, as well as a standard rival. Sort of like RSE and DPPt, but with more interaction than a few of random battles. It always made me a little sad that whoever you didn't choose in FRLG just didn't exist. And I really liked having two rivals in BW. They each had different motives and personalities. I'd also like to see the second rival be female, and maybe a bit more like Silver or Blue; caustic and competitive, while the opposite gender PC has more of a friendly, helpful rivalry.