Although you may have already seen this video, just watch it and hear what he says around the 50 second mark. This is why I'm not giving my hopes up on the extra characters, although Boon may be known for bullshitting.
http://www.gamespot.com/ps2/action/mortalkombatdeception/media.html
Watch the 4th movie down.....the developer interview. Around the 50 second mark, listen to what he says. I know some or many of you may believe that there are really no super unlockables, but this video is a reason not to give up hope. I know it's old, but could still hold true. Edit: Watch the Puzzle Kombat section towards the end, Li Mei and Hotaru can be seen in the mode. Just think to yourself "Why would they make the Puzzle Fighter models if theyt aren't going to use them?" I personally think the Puzzle Fighter models are just the regular models with everything smaller except the head, but even if this is true, they should know that some people would want to be Smoke, Noob, Liu Kang, or even Tanya. I have a big feeling that the rest of the puzzle characters are indeed accessible without a cheat device or codebreaker.