There is none.
There isn't currently a code for all of the legendary pokemon, but they each have individual codes in Heartgold DSi Action Reply. check out this guy's channel on YouTube. He has most of the legendary pokemon DSi Action Replay Code for Heartgold. ☺ :)
it helps you go back in your game if you didn't catch a legendary Pokemon
There is no specific code that allows only legendary Pokemon to appear. However, there are Pokemon modifiers. Use these at your own risk.
action replay max does but shouldn't(does not work) and i am not sure if the regular action replay does.
Well in heart gold you can use a action replay or just find them like everyone else so I hope i answered your question.
You can't. It is impossible, even with an Action Replay Code.
it is 94000018 910fga81 ca61g211 90df5600 d2000000 00000000 ITs fake there is no G in action replay
you can trade
Through an action replay code
catching trainers Pokemon
No, there is not. Sorry...
Use a action replay