I just realized something. You can't play and finish Phantom Hourglass with the 2DS! There's one puzzle where you need to close the DS, which you can't do with the 2DS
You can "close" the 2DS using the SLEEP slider. The puzzles will lose the original meaning nevertheless.
E.g. Another code's puzzle where you try to stamp something by closing the DS, is logical when the DS is really closed, one screen over the other. You should be able to do that with the SLEEP slider, but it won't make sense. Now for the puzzle where you should look at the reflection of the top screen in the lower screen, that one would be really hard to figure out.
yeah I wonder why people interpret things so wrong. In a News post I saw somebody saying that the Sleep Slider of the 2DS is the new Power button even if there was clearly a separate Power button. But The Quest wont make any sense. Closing a DS was somewhat logical. Making your ds go sleep makes no sense at all.