You can.
you cant. You can only catch it in Pokemon emerald, but, you cant catch latias in emerald.
you cant
you cant catch them you have to evovle trapinch
u cant
you cant
you cant you have to migrate it from Pokemon emerald
you cant get regigigas on Pokemon emerald its to ew of a Pokemon
you cant you have to migrate it from emerald
you cant unless you use action reply
You cant on Emerald, but i believe you can catch and transfer them from FireRed and LeafGreen.
You cant catch a wild ludicolo. You have to evolve it from a Lombre
you cant catch rayquaza you must trade it from emerald