breed it
Dialga is level 47 in Pokemon Diamond and Pearl. Level 70 in Pokemon Platinum. Level 1 in Pokemon HeartGold and SoulSilver.
You can't unless you cheat
Suicune is at Level 40 in HeartGold and SoulSilver.
By training your Pokemon.
you cant if you make an egg it will come out as togepi
Level 18
Level 20.
level 30
Level 55
lugia is level 45.
level 28
You must "endlessly" train your Pokemon.