After 3 heon legendery whats next ?

I've beet Rayquaza but i can't find what to do after , help please ?

also , after i slept in monstro town inn i've realse 3 pokemon , but  i went into the purple place that pipes leads to them but they arent there ?

 If you're in postgame, frog is the answer to anything and everything until you're not strong enough for what frog's answer is, or you're nearly done with frog. So just go to frog.