u cant.. only in platinum
you cant get all the regis only regigigas.
you can find them in either Kanto, Johto or by trading Pokemon with other people
you get a diploma
everywhere
Actually you're wrong you can NOT get the regis in Pokemon diamond, to get the regis you need Pokemon ruby/Sapphire/emerald you can get all three regis there(regi ice, regi steel, regi rock) althought if you migrate all of the regis onto Pokemon diamond you can get regi gigas(king regi) you will find him in the snowpoint temple after beating the elite four. Thanks hope i helped ^.^
Proffesor Oak will give it to you after you get ALL the badges!
well, when you catch all of the regis in either Pokemon ruby, Sapphire, or emerald put them in Pokemon diamond or pearl using pal park and you will be able to find regigigas
Profeser gives it to you after you get all ehgit bages
there is a mew in Pokemon soulsilver but you need to catch all leadndery Pokemon including event Pokemon
Yes all Pokemon can follow you onheartgold and soulsilver. Think of a blastoise following you.ahhhhhhh!!!
you can't get the three regis but, if you have pokemon sapir\rubi\emerald version on the gameboy advance, you can tke the three regis through the pal park in route 221 (in south). *there are three caves that may be the caves of the three regis but i don't know what to do there.
almost all of them do.