Unrullitarulli

Hey, I'm new to this game! Just started playing last night. I beat Brock with 2 lvl 15+ pokemon, and a bunch of lvl 7s and I was wondering where/ how I can lvl up those lvl 7 pokemon, what is the shiny rate (shiny charm?!) , and how long would this game take to complete/is there alot to do after the game besides bosses, and what are quests. Thanks guys -UnrulliTarulli