Yes, you can, just like any other catchable Pokemon.
Though the catch rate is reduced, it is completely possible to catch Dialga without lower its health. It is recommended to use a Quick Ball on first turn to improve your chances. Of course, the Master Ball can be used to catch Dialga at full health too.
20%.
neither of them is better, they are both the same, but in diamond, you catch dialga, and in pearl, you catch palkia, and you can catch different Pokemon in each game for example: you can catch this Pokemon in diamond, but not pearl but: you can catch this different Pokemon in pearl, but not diamond
You catch dialga/palkia on spear pillar inside of Mt. Coronet for diamond or pearl
You can catch Palkia in Pearl and tranfer Dialga to pearl from diamond.
Easy if u dont catch DIALGA and you kill it, it will say dialga vanish or soming
You cannot catch palkia in diamond and dialga in pearl but you can catch both of them in Pokemon platinum
You can only catch dialga in dimonid
after you catch dialga
Spear Pillar
No you cannot. You can only catch Dialga in Pokemon diamond and platinum. Although you can only catch palkia in pearl and platinum.
This makes absolutely no sense. You catch Dialga at the Spear Pillar in Diamond or Platinum.
20%.
In a way. In pearl, you catch palkia. And in diamond, you catch dialga.
you can trade with someone that has a dialga in pokemon diamond
neither of them is better, they are both the same, but in diamond, you catch dialga, and in pearl, you catch palkia, and you can catch different Pokemon in each game for example: you can catch this Pokemon in diamond, but not pearl but: you can catch this different Pokemon in pearl, but not diamond
You catch dialga/palkia on spear pillar inside of Mt. Coronet for diamond or pearl
You can catch Palkia in Pearl and tranfer Dialga to pearl from diamond.