So is there one account for all the pokemon games? or is there just one for each of the pokemon games.... and how would you trade to yourself to put pokemon from one generation to another??? Like if you save in a generation while on another, what happens?
if there is one account for all pokemon games, what does it use?
I'm unsure if I understand the question correctly, but to "Trade" Pokmon from a Generation to another, there are different methods depending on the Generation. Pokmon can go on newer Generation than they are, but they cannot be brought back into an older Generation.
To transfer Pokmon from Gen 4 (Diamond/Pearl/Platinum/HeartGold/SoulSilver) to Gen 5 (Black/White/Black2/White2), you need 2 consoles, and you need to have access to the Pok Transfer Lab in your Gen 5 game. It explains how to proceed directly in the facility.
To transfer Pokmon from Gen 5 to Gen 6 (X/Y/OmegaRuby/AlphaSapphire), you first need the Nintendo eShop application "Pok Bank", then you need to download Pok Transporter from the Pok Bank app. However, you need to pay for this service.
To transfer Pokmon from Gen 6 to Gen 7 (Sun/Moon), you only need to use the Pok Bank.