How do you get to Eterna City in Pokemon?

So you got the Oreburgh city gym finished and you got rocksmash. well, all you gotta do is to teach it to a Pokemon then use it to get through ravaged path then you'll be in floaroma town. you'll have to defeat the team galactic people there then you gotta get through eterna forest.If you find that difficult (defeating double battles) walk up and talk to ONE of the double, without walking through them. this will enable you to fight them one at a time, which makes it easier! when you've done that, you're in eterna city!