With the release of the games Black 2 and White 2 we released the battle style B2W2. When I had suggested it probably close to a year ago (a suggestion that went nowhere until it was brought back up many months later), my idea with it was to have a fair battle system of sending privately but that still allows the flexibility of DPPt so that battles such as Elite Four, Champion, Legend Defender, and Tournaments could be done under a more flexible ruleset. However, so far no Tournament has allowed it as a rule (unless Keldeo happened since it was released, but if so that was only because Keldeo allowed ANY ruleset with only one or two restrictions (4v4+ iirc)) and it's not a legal rule in Elite Four, Champion, or Legend Defender, and I'm not sure if it's legal in Orange Islands (though only Mikan and Pummelo could use it without violating their special rule, technically Kumquat could use it too to allow picking items and abilities when you send it out but still having the Pokémon predetermined).
Logically the reason that rules such as DPPt shouldn't be allowed in these situations is because of the unfairness introduced by sending publicly, especially the massive disadvantage of whoever sending first, possibly also requiring people to be good at predicting due to how important these battles are. B2W2 fits these restrictions, while still adding a new level of strategy. Additionally, in Elite Four and Champion it would obviously only get used if the Elite Four member or Champion wants to use it. In Tournaments, if it's not the default rule, either battler could say they don't want it and then it wouldn't get used. Only in Legend Defender, where the challenger is allowed to change one rule, would it be possible for it to be thrust upon the defender.
Right now B2W2 is really only used for fun battles. I think SLC uses it in Dewford, but other than that I don't see it used in anything important. Most gym leaders either prefer DPPt for a variety of reasons, including forcing the challenger to send first, or Revolution, where they can limit the challenger's pool of Pokémon to the same size as their own. Personally I like being able to pick my Pokémon as I go, even if it puts me having to pick constantly from 12 while my opponent can pick from as many as about 200 (YES, I'M LOOKING AT YOU BEE), and I would use it in my Elite Four Reserve position given the option.
I'm putting a poll on this thread, I'M SETTING IT SO YOU CAN PICK MORE THAN ONE OPTION, so pick all that you agree with.