Gen VI is gonna be great for you OP. It was pretty much designed specifically for genwunners, nostalgiafags and lapsed fans from Gen I and II.
It has lots of throwbacks, lots of classic Pokémon and most of the stuff that was added in later gens are hidden off to the side somewhere.
All you need to know is now Pokémon have Abilities, which they're born with and are basically passive skills from other RPGs, and Natures which dictate how a Pokémon's stats grow. Oh, and Attacks have been split into two categories: Physical (damage determined by the Attack stat) and Special (damage determined by the Sp. Attack stat), and I'm sure you can figure out from that what Defense and Sp. Defense are for.
Most of all just go in with the mindset of wanting to have fun and not pick apart every tiny detail in the balance.
