You have to evolve it from an Aron. Arons can be found at the Fuego Ironworks with a PokeRadar. Then you level it up to 32 and you get a Lairon. If you want to evolve into a Aggron as well, level it up to 42.
I don't no I just beat the game and i think its either at Mt. Silver or some other place where you might think Lairon resides but i do know you can you can migrate an Aron onto Pokemon Diamond from Pokemon Emerald and trade it to Pokemon Heart Gold.
Victory road =]
You can not find or get manaphy on Pokemon diamond but you can by hacking, trading or... if you have Pokemon ranger you have to complete the manaphy mission and then you can put it onto diamond.
You can't find a Ho-ho in Pokemon Diamond. You have to migrate.
Get Lairon To Lv42 and it will evolve into Aggron
at level 42
a cave
get to a certain level above aron and lairon
Lairon is a Rock and Steel type pokemon.
I don't no I just beat the game and i think its either at Mt. Silver or some other place where you might think Lairon resides but i do know you can you can migrate an Aron onto Pokemon Diamond from Pokemon Emerald and trade it to Pokemon Heart Gold.
Aron will evolve into Lairon at level 32, then into Aggron at level 42.
you have to get lairon toLV. 42 OR 43 and then Lairon will evolve into Aggron
at level 42
The Pokemon exclusive to Pokemon Diamond are: Seel, Dewgong, Scyther, Scizor, Murkrow, Honchkrow, Larvitar, Pupitar, Tyranitar, Poochyena, Mightyena, Aron, Lairon, Aggron, Kecleon, Cranidos, Rampardos, Stunky, Skuntank, and Dialga.
I'm not sure trying to find out myself, sorry.
Lairon thrive in the Safari Zone. Breed to get Aron.
Lairon evolves at level 42-45 in Pokemon Emerald version.