no its not that hard. its the same story plot.
No
Leafgreen and Firered, Pearl and Diamond
you can get Pokemon that are not in the other version
No
No. Riolu did not exist during Generation III, which was the generation Pokemon FireRed & LeafGreen versions were set in.
You can trade them through a link at the Pokemon trade center
That would be FireRed/LeafGreen/Ruby/Sapphire/Emerald.
I think you can only pass Pokemon from Emerald to Diamond/Pearl
You can trade between firered, another leafgreen, ruby, sapphire and emerald also Pokemon colosseum and Pokemon xd gale of darkness.
it is like Pokemon gold,silver,firered,leafgreen,yellow,Sapphire,ruby and emerald versions
Nowhere. You can't. You have to trade them from the FireRed and LeafGreen versions.
You can't get mew in firered or leafgreen.