you can't unless you have game shark or other cheat codes
There is no best Pokemon on Pokemon HeartGold.
there is no Pokemon Mansion in Heartgold.
Regigigas
Nope, you can't battle Lyra at all at any point during the game in Pokémon HeartGold.
They are not in Pokemon HeartGold
There is no best Pokemon on Pokemon HeartGold.
there is no Pokemon Mansion in Heartgold.
in the temple in snow point
Regigigas
Nope, you can't battle Lyra at all at any point during the game in Pokémon HeartGold.
They are not in Pokemon HeartGold
snow point temple. two rare Pokemon
where is the pokemon transfer lab in heartgold
when you defeat the Pokemon league and get your national pokedex.
snow point gym
use a pokemon to use fly to snow piont city gym and go to the harbor on the north
No, but you can trade Pokemon only in HeartGold to Black