What Do you do after you beat Jasmine?

Answer 1

For HeartGold/SoulSilver:

If you have already beaten Chuck and Pryce (in Mahogany), then you will get a call from Prof. Elm. He will say that there is something weird in Goldenrod City. Go there and you will find team rocket in the radio tower. But you must go to the underground in Goldenrod and the guy at the top will dress you up as a Grunt. You then can sneak in to the base, and the game progresses from there.

For Silver/Gold/Crystal:

I think you can just go into the radio tower and the game progresses from there.

Answer 2

After you've beaten Jasmine you will need to head to Mahogany Town via Route 42 and then once you make it to the town you will need to head north to Route 43 and continue on your way north until you reach the Lake of Rage you will need to go into the water via a Pokemon that knows Surf in order to find the Red Gyarados which is at Level 30 at which point you can encounter it in an attempt to catch it but after the battle ends head south to find a guy with red hair who is with his Dragonite, interact with him and he will introduce himself as Lance and he will ask you for some assistance back in Mahogany Town so return there.