im sorry i don't think you can however when you catch dialga in Pokemon diamond it will say you saw him in the sinnoh pokedex i hope this helped
acyaly you can with a cheat, and it NOT for acton replay!
The Pokemon that can be caught without special events, trading, or cheating in Pokemon diamond are: Uxie Mesprit Azelf Dialga Giratina Heatran
no you can't you have to either trade or gameshark cheats :P
You can if you use action replay :P If you don't use one, then it is impossible to complete without trading as there are only certain Pokemon that can be caught in diamond and vice versa with diamond.
No it is not possible. You have to hack or trade.
You can't without cheating. Unfortunately I'm not aware of a cheat that can do this yet.
u can't
Without trading or cheating, you can't. It's a Pearl exclusive.
The Pokemon that can be caught without special events, trading, or cheating in Pokemon diamond are: Uxie Mesprit Azelf Dialga Giratina Heatran
impossible. u cannot get dialga without trading from a diamond game but the rest u can do.
It is impossible without trading from Diamond, Pearl, or Platinum, or without the use of a glitch or cheating device.
No not every pokemon. You can't catch the starter Pokemon and many of the rare pokemon, you have to trade with Diamond. sorry ...
Without trading, cheating, or Nintendo events, you can get Dialga, Uxie, Azelf, Mesprit, Heatran, Giratina, and Cresselia.
Impossible without cheating.
Cheating, hacking, or trading.
Without trading or cheating, it's impossible. You can trade from HeartGold/SoulSilver or get it from Pal Park with FireRed or LeafGreen.
Special: Unobtainable without cheating or hacking, or by trading with someone that has done so.at Level(s): 80
Not without trading or cheating.