You'll need to buy it with points at the Pokeathlon Dome.
a murkrow or a misdreavus.
lampent
in mistrilion cave
Murkrow -> Honchcrow Misdreavus -> Mismagius
You can get a Duskstone in Firered by simply migrating one from either ruby sapphire or emerald or diamond pearl or platinum
The Pokemon that can evolve once you use a Dusk Stone on it are Doublade, Misdreavus, Lampent and Murkrow.
Get first place in the Bug Catching Competition, although you might not get it.
Evolves Misdreavus into Mismagius. Evolves Murkrow into Honchkrow. .
There is no best Pokemon on Pokemon HeartGold.
there is no Pokemon Mansion in Heartgold.
They are not in Pokemon HeartGold
where is the pokemon transfer lab in heartgold