Okay, so I want to use Challenge mode on my White 2 playthrough when it comes out, but I don't want to play all of Black 2 first. Would it be possible to use an Action Replay on my Black 2 copy, unlock Challenge mode with it, and then transfer it to White 2? Then I could delete my save data on Black 2?
It's generally a bad idea to use an Action Replay on any Pokémon games and I'm not aware of a cheat that unlocks Challenge Mode, since I think you can only send Challenge Mode to W2 when B2 has a finished save file on it, but don't take my word for it.
"Evil, beware. We have waffles..." - Raven, Teen Titans
When you legitimately unlock Challenge Mode by completing the game, you receive a Challenge Key that can be used on other save files to unlock Challenge Mode regardless of the other game's progress. However, a "borrowed" Challenge Mode can't be further transferred to another game, because the key itself does not transfer. Black 2 can only transfer Challenge Mode after unlocking the Challenge Key, and White 2 can't transfer it at all.
If the AR code unlocks the Challenge Key itself, you should then be able to transfer it to White 2 (unless the game checks whether or not you beat the game regardless of whether you have the key, which is a possibility). If it only unlocks the Challenge Mode option and not the key, the game will likely assume you received it from another Black 2 game and will not allow you to transfer it until you beat the game and legtimately obtain the key.
Just started challenge mode by using an Action Replay code to unlock it so I can play it on cartridge...
Luckily my Mijumaru turned out to be female without even soft resetting for it. Tsutarja wasn't so bad, it never watered down my Pokémon's HP to red yet. When I reached Sangi Town, it was raining and that benefit Mijumaru's STAB even more. No need to use Tackle when you have Water-type + STAB, that nearly 3HKO'd Tsutarja in the 2nd battle against Hugh.
Pokemon Black Friend Code: 3525-9345-0509 Pokabu PGL Nickname: Chillarmy07 http://en.pokemon-gl.com/profile/?id=3047996#/