Let's see, what do I want to see in the next generation...
- More battle animations. Mainly some or all Pokemon having slight animations just while sitting there. For example Zubat flapping their wings. I'd also like to see 'getting hit' and fainting animations for Pokemon. But that might take up a fair bit of room in the DS cart. :P
- Following Pokemon making a return. Also IV breeding items like in HGSS should make a return. As well as apricorns making a return.
- An IV cap. For example, while you can have a maximum of 31 IVs in a particular stat. But only a total of 124. Obviously how Hidden Power is calculated would need to be reworked.
- The RNG being reseeded on start-up again. every saving method being properly checked for duplication glitches. Abilities being constantly updated based on their personality value so that we don't have to worry about WonderTombs.
- More legendaries. One in an Unknown Dungeon sort of thing, one required for the story, one in a spin-off game, one event only Pokemon and all the rest being optainable in-game via side quests. If Nintendo want more events, they can use old generation Pokemon.
- More modes in the Battle Frontier. That is open level and six Pokemon teams. And more online play in the Battle Frontier.
- Heaps to do after the Pokemon League. Platinum's about right. That is an extra area with heaps of stuff and a Battle Frontier.
That's all I can think of at the moment.