Normally you need an AR, or a master ball, because once I had mesprit at 1 health and I couldn't catch it so don't try.
In Pokemon diamond you can catch Dialga, Azelf, Uxie, Mesprit, Cresselia and Arceus
you cant get it without migrating.
There is no other possible way of getting suicune without migrating or action replay its a legendary anyway and you just get them for show
no
Dialga
Near Hearthome city.
no
you cant get every legendary of Pokemon without cheats or migrating and trading with people
Trading, Migrating, Catching the legit legendary Pokemon in pearl, etc.
You can't find Rayquaza it in pokemon diamond, pearl, and platinum. You just migrate it in Pokemon Emerald, ruby and saphirer
u can't
U HAVE TO MIGRATE OR ACTION REPLAY