In the top of the battle tower
You can't get rid of HMs in heartgold.
double click on them then click toss
The code is: 1356475a 89065865 00000000 00000078 90765937 98765000
train your pokemon up to level 80,90, or 100 and teach it TMs and HMs
rock smash water fall strengh surf and flash
The only way to delete moves is through the Move Deleter, which should be in Blackthorn City.
no
fly, cut, surf, waterfall, rock smash, strength, and rock climb (don't get till you beat all 16 gyms, from prof oak)
Pokemon HeartGold can communicate with all the DS Pokemon games. :c)
cut, surf, fly, rock smash, rock climb, strength, and waterfall In Diamond, Pearl and Platinum there is HM defog. In HeartGold and SoulSilver there is HM whirlpool.
I put a link to a guide all about legendary pokemon in HeartGold in the related links.
You catch them all....