If your talking about the mansion with the rooms the maids are gaurding , You cant not even with ar you just go in to a black screen if you use walk through walls cheat.
You can find out how many times you have beaten the Elite Four in Pokemon Diamond by checking your PC in the game.
12 times
Chimchar evolves twice in Pokemon Diamond Version. From Chimchar to Monferno to Infernape.
One each.
13 times or more
Easy all you have to do is beat the elite four 15 times without healing you Pokemon
some times they do or sometimes it will just have a different code
yes. ive done it plenty of times
you have to beat the game 50 times then u get an event
ABSOLUTELY NOTHING =D take this from a person whos been through the league 30294230940 times
i duno but try sometime when it gets dark, because you meet darkrai inside in a dream so it must have to be dark because darkrai is a dark type pokemon.
Absolutely Nothing.