Latios, Groudon, and I think the three old Regis (this doesn't include Regigigas), I'm not sure about Jirachi...most likely Jirachi is in Ruby
You can get three rare candies in Pokemon ruby sapphire and emerald
...and?
Solrock is not such a rare Pokemon but you can only get them in ruby/emerald
n e where
You catch them. Or trade for them.
Groudon is rare and you get him just by following the story line. The only other "rare" Pokemon I'm aware of in Ruby would be Relicanth, a rock/water type fish Pokemon that can be found underwater.
Rare Pokemon come randomly when you're in the grass or cave.
use the itemfinder
There are a few rare Pokemon you can get in the safari zone they are pinsir, wobuffet and girafarig.
i think there's none
Pokemon ruby sapphire and emerald
you can get feebas on route 119 very rare