This really made my day! My sister and I discovered a familiar tune in Castelia City while playing Pokemon White! Head over to the "GAME FREAK" building on Castelia Street, alright? Go up to twenty-second floor and talk to the man with the male Ace Trainer overworld sprite. That's the guy with blue hair. I'll leave the surprise up to you guys . If you don't have Pokemon Black or White, or if you just give up, ask me, and I'll tell you XD. Hints: It really made me feel nostalgic, my first game being Heart Gold... Alright! I'll give 100 Viz to whoever tells me what theme is first! Good luck! 

NintendoFanKimmy : i have BLACK 2 dosen't  work also in this game? also no need 100 Viz no thx!

greenluigi : I'm not sure if it works in Black 2... You can try and see if you want! And, no, green, it wouldn't be fair if I didn't give you Viz XD.

NintendoFanKimmy : black 2 didn't work

greenluigi : What do you mean it didn't work? The easter egg, or the game wouldn't start up?

NintendoFanKimmy : i dind't saw an ace trainer

greenluigi : Oh, so it doesn't work in Black 2. Sorry XD.

Yep I have done this too. The theme is the Team Rocket Theme from Heart Gold and Soul Silver. Personally I prefer the original 8-bit sound version on the Gameboy colour trio because it has more of a retro feel. The remakes of the original Johto games were not as good as them, I guess the Graphics and Music were enhanced but the game just played really slowly, battles last for ever in modern pokemon games it can get boring!
Don't bother with the Viz though I already have 90,000+ Viz already. Also you and...
greenluigi :

Can you both stop using posts to make conversation. Yes it may be fine in some cases such as discussion threads yet in threads like this it will look spammy. You are advised not to sandwich posts, it is not a massive rule but people do get annoyed by it and yes it is also considered spam.
This is just a heads up to the future...

MechaMento : Thanks for the heads up, MechaMento! And are you sure you don't want any Viz?