Well if you dont have cheats or event codes, then there are 8 i think, dialga, cresilia,giratina,the three spirits(that you have to chase around),rotom,and heatran
5
One each.
the legendary Pokemon in diamond and pearl are dialga and palkia.
No, a Bidoof cannot evolve into any Legendary Pokémon in Diamond.
Heatran
a lot of legendary Pokemon
Dialga
you cant unfourtanately
arceus
only 2 red gyarados and palkia
you can't catch it because you already beaten the legendary
no