I just saw a commercial on tv that said it was "available on 3DS and 2DS." Doesn't this mean that it's playable on a 2DS?
Yes it is true. Now don't get confused with the DSi/DS/DS Lite ect... The 2DS allows 3DS games but without the 3D graphics.
Source: Looked it up :P
yes, the 2DS can play all DS/3DS/DSi games (and not GBA) It's essentially a 3DS with no hinges or 3D capabilites (great for little kids)
:)
http://bulbapedia.bulbagarden.net/wiki/Nintendo_2DS