Board 8 > Which change to Pokemon battle mechanics was the most significant?

(+) Yeah! (+)

I was thinking about this last night and it was trickier than I thought to pick one. What do you think?
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I'd say double battles since that's the official battling format for the VGC now, even though singles was the original format
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This poll is missing the actual biggest change, which is the EV revamp from gen 3.

It affected two things:
1. Previously all stats could be maxed at once; now only 2 at most (or less if you spread them around), leading the concept of different "builds" for the same Pokemon. This increased strategy in Pokemon building and also made attackers less tanky and tanks less powerful, allowing for better "roles".
2. It actually became possible for a human playing on cartridge to reach the EV cap within their lifetime without grinding.
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I still don't get why the physical/special split is so praised for "changing" things; all it did was shift them. Some Pokemon got better and some got worse on a case-by-case basis, just depending on their individual learnsets. But it didn't alter the way that battles actually function like most of the things on this list.
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Double battles is the 'official' answer, and true of the actual formal game.
But in terms of the informal pokemon community which is still focused on singles, the answer is probably the EV revamp as hotdogturtle pointed out - followed by abilities, held items, natures, and then the two splits. In roughly that order, albeit pretty close together.
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Ah, damn, I knew I would forget something. Oh well, I guess this poll is just for mechanic changes that were actually announced. <_<
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