Dual type moves- I know people already suggested this and some found it difficult to find a solution. It's simple, thunder rain - electric/water, calls out a rain that powers up water type moves for 2 - 5 turns and strikes the opponent with thunder on the first turn.
Or Dragon Thunder - Dragon/Electirc, simply one strike with 150 power. Weakness and Resistance to Dragon and Electric apply at the same time.
Better Pokemon designs, this is just my opinion but I dont feel proud of myself when I do so much in the games and go on my adventure defeat strong opponents with crappy design pokemon, again it's just me.
Pokemon apps - i'm talking about something like what we got in Platinum, I found it very useful such as the item finder and the steps count.
It would be really nice if they could make some real time apps. For example a dream radar app for the phone where you could access dream radar via mobile phones. They could have other apps too which could have enjoyable features such as the Pokemon Amie, an app that lets you buy, sell accessories, character customization, trade rare items which could only be achieved by this method and so much more which then could be applied in game from the apps.
A good storyline, longer game with good gameplay mechanics and more exploration with rewards.
More Pokemon being obtainbale in a unique way - Most Pokemon are not that hard to get, in black 2 and white 2 I was able to get almost all of them by trading. Now this is good but think about how rewarding it will be when you go on a quest to get an item, then that item on a different place which opens a cave, explore the cave which gives you a hidden TM that lets you access an area in a different side of the map which contains a rare species of Pokemon now ofcourse this is all optional. They should some Pokemon extremely hard to obtain this is just my opinion but it makes me feel special about my Pokemon.
Can we carry 8 - 10 Pokemon with us? Atleast 8 because there are so many Pokemon that weball love. Fair enogh we can't use them in battle but atleast carry them with us and able to switch them into your party outside of battle. This can make training a lot easier.
In Univa we learn that there are more than 8 Gym Leaders. Why not do the same in game but you only have to beat 8 to gain access to the Pokemon League, defeating the rest gives you additional rewards.
More items that is useful outside of battle such as the item finder, it will make the gaming experience fun besides the battles.
Need a Rival like Silver - Ok people might say a lot for this one but think about it it's been too long since we had a rival like him, the new ones are so friendly and cheesy. We need a badboy like Silver or atleast Blue.
Items that you could have to your Pokemon that works in different unique ways changing the battle style to a unique way apart from factors like type and stats. Also these items should be achieved in a unique way like online rank battles, exploring hard dungeons/caves, dlc etc
Customizable profile for online multiplayer
New game plus - well I dont know how this is going to work but every time I finish the game I really dont like deleteing my old game data and starting all over again deleting all my achievements.
Apart from the new game plus mode, i dont really like any of these ideas. If they can keep Black/White as a standard for story i would be happy, I find dual type mvoes to be a dumb idea in the first place, because it would dumb down having type coverage across your team when you can just put 4 moves onto a pokemon that cover 5-8 types, and even having the ability to STAB bonus them all. The 8-10 pokemon with you seems exesive, if there gonna keep HMs, why not have a 7th pokemon with you for that purpose, helping you travel through out the world. Would love just keep a Bibarel for all of my HM needs on me at all times. EIther that or give a pokemon an "HM" slot where you can teach them one HM move that they can use only outside of battle. The newgame+ would be nice, along with adding many more pokemon to each route for that newgame+ mode. As for getting pokemon in unique ways, we had spiritoumb, and he was just too anoying to get, plus it still wouldnt solve the fact that youc an still get whatever you want from trading anyway.