you kiss him with palkia
you have to get the cianwood gym badge and the olivine gym badge
You go back to Golden Rod city and u notice that team rocket has taken over it
you have to go to the guy blocking you from blackthorn city
he's the tubby guy in the house to the left of the Pokemon center in blackthorn city
After you beat the gym leader before Clair that guy that was blocking your way before will let you through.
Blackthorn City Gym is available to challenge after you defeat Team Rocket in the Goldenrod City Radio Tower and make it through the Ice Path.
You have to beat team rocket in goldenrod city before you can go to blackthorn city.
you don't go that way, instead you go though dark cave (you need rock smash) to reach blackthorn city
you show him the rainbow wing
in a house in blackthorn city. he teaches meganium frenzy plant, typhlosion blast burn, and feraligatr hydro cannon.
You will not be able to get past this guy until you have defeated Team Rocket in Goldenrod City and have beaten Pryce the Gym Leader. Once they are defeated, the guy allows you to go past.
You ride on a unicycle there Actually, you beat Team Rocket in Goldenrod City. After that, the guy blocking the way in Mahogany Town should move.