If I'm not mistaken, you have not much left to do with the story.
All you have left to do are:
1. fill your Pokedex. (you will need to trade from other games like SS)
2. go shiny hunting.(for your usage or trading)
3. train the pokemons to Lv.100 with EVs and such so that they can be awesomely strong to battle other people's.decide your teams 1st though.there isn't any point in training individually because you need to decide the moveset or role of a pokemon.
4. wait for the events and go get those event presents. Because, some event things can unlock secret places, catch secret pokemons for your story.
Edit: Credit to Victini Victory. These are his answers. Wanting to add some links for someone who just started playing to be able to know, I added here.+his comment.