What do you do after you beat misty in Pokemon HeartGold?

Answer 1

Explore! Run around! Return the generator if you have not already! I took on all the gyms in stead of hanging around, and now Blue is going down! But that's not the point. Your "mission" in Kanto is to collect all 8 badges, and defeat trainer Red. Keep figuring it out, and start heading to Lavender Town. Get a new radio card, for kanto. Take yourself to Vermillion. Go East to the snoring snorlax. Open pokegear, put radio signal at very top, and Flute will play. Press A at the Snorlax, and it will become awake, and decide to battle you. It is lvl 50, but not very hard to catch. it is also very helpful. Now head through Diglett's tunnel. You can go anyway once you emerge, but that's the gist of it. Don't forget to go running around with the other gyms, too, though.=D Hope it helped.
Have you defeated all four other gyms where you can go? If you have, then you have to go to Kanto's Radio Tower. There is a gentleman inside. Talk to him and he gives you some new radio channels. Then, you go to Vermilion City, go right to east. Then, there is a Snorlax. You put Pokégear's radio, and the ball to up. Then Snorlax will fight you. And after the battle, you go to Diglet's Cave. Then you can fight against Brock.