Seeing as RSE was easily my favorite generation, I have a huge amount of things I want to see, and also a huge amount of things I don't want. To make this much simpler, my biggest hopes for them not screwing things up are bolded.
- Like mostly everyone, I'll be unimpressed if Wallace is the champ again. Steven is just an all-around better trainer. Multi-type as opposed to water mono, and just overall better Pokemon.
- Don't make this game a cakewalk! I want this game to challenge me, unlike X and Y. It was pitifully easy to walk through X in two days. I want to see MUCH steeper level curves; difficulty spikes with the gym leaders and E4; full teams for E4 and at least 4 Pokemon per gym leader; an EXP share that doesn't practically level your entire team to 70 pre-e4; a much smaller regional dex than X and Y (just add Hoenn family additions from later gens); and most importantly - no megas until after the e4. This brings me to my next point, which is unrealistic to say the least.
- I hope they don't embrace Megas too much. Act like megas never happened! I absolutely hate them and wish that Nintendo would erase all traces of mega existance. They just make me think Pokemon is ready to retire. Why else would they crush Mawile's potential after it gained Fairy typing like that? An actual evolution would have been so much cooler and more fulfilling. Plus, did Blaziken, Garchomp, and Tyranitar really need megas?
- Don't put out a game that looks dull and doesn't take full advantage of the 3DS's graphic capabilities. I wish they'd really go all-out with the aesthetic aspects of the game. I want the open world to be breath-taking and immersive. I want there to be details in the trees, the ocean floor or river beds, maybe more detailed HM animations for Fly/Surf? Unless I'm using Wailmer to surfer, I don't like sitting on a black blob floating across the sea. hell it'd even be cool to see Pokemon scurrying to and fro or sitting in trees in the wild, though that's highly unlikely.
- Don't give us the same fleeting rivals that show up a couple of times and never amount to anything. I want them to think the Rivals' roles through carefully. I want both Brendan/May and Wally to have established personalities and I want them to set goals and establish paths to achieve those goals. I want to know what happens with them, for crying out loud!
- Don't sell the game short and practically end it at the E4. I want some new content. I want a ton of side quests. I think it'd be awesome to see what becomes of the leaders of magma/aqua, or to follow up on Wally and your rival and give them more spotlight. Maybe actually add a Deoxys storyline or a Jirachi storyline. It'd be harder for Latios and Latias, seeing as they roam, but I wouldn't complain if they became stationary legendaries (Hell, they're practically impossible to find as roamers) I know it isn't all that common for Pokemon to have in-depth stories and multiple side stories, but I think it's a direction that could definitely add a new level of entertainment to the series. Plus, there is a ton of wasted potential in places like New Mauville, the desert, Shoal Cave, Meteor Falls, Pacifidlog town the abandoned ship, and mirage island that desperately need to be reconsidered and given a second chance to at least have bigger parts in the main story.
- Don't make me bike through the Sky Pillar. This seems unlikely, though, so at least just give me more control of the Mach Bike.
- Don't halt the progress made with X and Y's character customization! We likely won't be able to change hair this time around, so add more to wardrobe choices! Maybe allow Brendan to take his hat off!
- Don't make a ridiculous amount of HM-dependent areas. I hate HM slaving Pokemon not named Bibarel, and I hope Bibarel won't even be available pre-E4, so just minimize the use of HMs!
- Don't make supposedly significant locations so small and insignificant. The desert was way too small. New Mauville wasn't exciting at all. All of the caves were pretty much pointless save for victory road.