What if pokémon could have 2 natures and/or 2 abilities? The neutral natures might actually get used if they have to be 2-dimensional, and get stats boosted by 20% for an extra nerf.
Hmm. Well, multiple abilities (heck, why stop at two?) is an idea that I like a great deal in theory; I think it could be particularly interesting for combining very powerful and very strongly negative abilities on a single Pokémon (say, Truant and Sheer Force, or Speed Boost and Defeatist). In practice I think you would have to run through almost every Pokémon that currently exists and give some careful consideration to how this kind of thing would affect their power levels. Some Pokémon like Zubat just have two crappy abilities and kinda get dicked over by this; other Pokémon have two really insane abilities and become significantly more powerful – imagine Reuniclus with Magic Guard and Regenerator, Yanmega with Speed Boost and Tinted Lens, or (gods forbid) Excadrill with Sand Rush and Sand Force. You’d need to be careful with it.
The natures… the natures I’m so-so on. I’m wary of the increased min-maxing potential that it allows. On the other hand, it’s likely that the second nature boost will actually have a real cost, because you can’t just say “okay, I’m going to penalise the attack stat I’m not using;” if you want to keep jacking up your attack or special attack you have to take a cut to speed or one of your defences (the neutral natures would still never get used, because every Pokémon is always going to have two stats that it cares about more than two other stats). That being the case, it’s probably fine-ish. I don’t think it really makes things more interesting though, is the problem, just more complicated. Also there are a few combinations that just feel very odd – like Bold and Adamant together work out as a bonus to defence and a penalty to special attack, which is just Impish. It feels weird to let them stack.