At the top floor of the Pokemon Tower
Chat with our AI personalities
There is no Gym in lavender town. You can find team rocket in Pokemon Tower tho
You go and ask the "rocket" over near the flower shop(at) the flower shop and go to the tunel and were the camara man was.
In order to bypass the guard, you must defeat Team Rocket and rescue the Director. You will be able to fight Team Rocket after you receive a phone call from Professor Oak, saying that there are weird transmissions coming from the tower.
Team Rocket's hideout is in Mahogany town. Team rocket can be found in the radio tower and in the underground basement in Goldenrod after you beat Pryce of Mahogany town (who cannot be fought until you take down team rocket in the same town), but they have no "hideout" in Goldenrod.
The Lavender Town Radio Tower is only accessible in the first floor in Pokemon HeartGold and SoulSilver. A security guard will tell you that after the takeover of the Goldenrod Radio Tower, they are stepping up security measures to prevent Team Rocket from hijacking their tower in Kanto.