Hmm, let's see... one thing I would immediately do is remove all overly-gimmicky evolutionary methods--such as turning your 3DS upside-down--and replace them with either level-up, trade, or stone evolution. Would most likely go with last one, since it's not that difficult when it comes to achieving; perfect middle-ground, if you ask me. Next, I'd introduce some type of Poké Ball that has much, much better capture rate than Ultra when using them on legendaries. This would reduce the need of spending so much money on regular Poké Balls significantly; only thing bad is that is might wind up devaluing Master Ball, but that should not be such a huge deal. They would still remain popular among people, since you're able to obtain only one throughout each game-play. Finally, I'd make it so that you're able to use certain moves in place of HMs. For example, instead of using Cut to get past small trees, you'd be able to utilize False Swipe, or perhaps even Slash. Instead of having to use Rock Smash to break small rocks, you would be able to use Mach Punch, Low Kick, or any other similar fighting-type attacks. This isn't my idea, though--somebody else had suggested it in some other thread--can't put my finger on who it was--but I personally like it. A lot, haha.