There’s this new fan game beta called Pokemon Evoas on deviantart. It’s like a pokemon game but they’ve made changes like learnable abilities, took out the steel, dragon, bug, and fairy types and added in metal and light, pokemon having more or less move slots, and instead of a villain team there’s this evil meloetta that controls trainer’s minds with music and has no qualms with killing. Might be worth checking out to see how these changes might affect the tone of the main games, if applied.

You know, this sounds worth looking at just to see how they work with the idea of a Pokémon villain outside of a Mystery Dungeon-type setting, especially one like Meloetta who’s normally viewed as more or less exclusively benevolent.  Other changes you mention sound interesting but not terribly exciting; I’ve gone on the record before as saying I don’t like the idea of changing the number of moveslots, and X and Y do actually introduce a way of changing a Pokémon’s ability (or at least, I think that’s what it does), the Ability Capsule (having two abilities at once, while very cool in some cases, would be frighteningly powerful for some Pokémon like Yanmega, so I am distrustful).  Not sure I understand the purpose of removing Steel as a type only to add Metal.