Before u start getting into pokemon galaxy I strongly suggest you play pokemon infinity instead. I dont play it but I used to. Its way better at like everything you can imagine. Only reason some people stop playing it is the quests and stuff get really hard the more you level up your character (example: catch 50 scythers). If you dont want a challenge, you can play pokemon infinity chaos instead its easier and I think its more fun tbh. You can click the link to it at the top of the page, or play the normal version.
I saw that on pokemon galaxy you dont move around a world.. you just click a map and try to find pokemon. On pokemon infinity you move around the world.. interact with NPCs.. do quests.. etc. And of course you can trade and battle with other players.
Hope you give it a try.
http://www.pokemoninfinity.com/pages/default/login.phpIf you try it and really like it maybe I could trade u some of my best pokemon for free