- New gimmick is about types. All pokemon can switch type one time while in battle. If a pokemon has two types, you can choose which one to change. When a pokemon change type it will be infues with the color of the new type, for example if Camerupt switched to Dark, a blackish aura appears around him. Same effect, with very small changes, will appear aroung Staraptor switched to dark etc. Some pokemon can change form while switching types, for example if you switch Camerupt to fairy, his back becomes like a flower garden with some sort of pink ring around it. No big changes in stats, it's pure fanservice. This mechanich is only available for some pokemon and some specific types. For example Camerupt changes form only if you switch to fairy. Rapidash changes form only if you switch to electro. Shiinotic changes form only if you switch to water.
Every type now has 2 counter-types, one which it is strong against, and one which is strong against it. For example fire is countertype to water and grass. Fairy is countertype to poison and dark. And so on. The countertypes are depicted on the big plaza we see in the trailer, every type has its countertypes next to it. The version we see in the trailer though is a little different from the real thing, some types are on the wrong positions. Pokemon can't switch to their countertype, for example Camerupt can never become water or ice (water being countertype to fire and ice being countertype to ground), staraptor can never become electro (since electro is countertype to flying).
Normal type gets a huge buff since it's the only type who can switch to any type. It sounds quite difficult but it's a very simple gimmick, way easier to play than to write.

- No national dex but there will be many more pokemon than sword/shiel (around 700).

- Many new pokemon will have very huge differences between males and females. Sometimes they will have different colors, other times they will look very different from each other.