Anything can be caught with an ultra ball. Even with a poke ball.
You are not able to catch the regis in Diamond. You can catch them in the Game Boy Advance version of Pokemon Emerald.
no
not. you will have to migrate them from emerald
You Can't
you can't catch them in platunim you will need to migrate the from ruby sapphire or emerald
you can only catch them in Pokemon emerald, sapphire, or ruby
You can fight in the battle tower, catch the three regis, search for latios/latias, or in emerald you can catch groudon and kyogre
You don't need to go in any order.
all i know is how to get the regis and latios or latias.
For Pokemon ruby you can catch the three regis, rayquaza, groudon, and latios/latias. In sapphire you can catch the three regis, rayquaza, kyogre, and latios/latias. However, in emerald you can catch kyogre, groudon, rayquaza, the three regis, and latios/latias.
The regis(except regigegas),raquanza,groundon,kyogre,and latios or latias
You need relicanth and wailord to catch the regis in sapphire/ruby/emerald. You cannot catch the three regis in platinum unless you have the event Regigigas (this event has now ended). If you have the special regigigas in your party, three new caves will open up in Sinnoh and you will be able to catch the three regis.