>>44751206I went to Bellsprout Tower to get a Ghastly, who knew Hypnosis.
It took like 6 or 7 tries, but I finally managed to put Miltank to sleep before its rollout killed Ghastly and keep it asleep until its death. This was my first Pokémon Game.
In a second run, when I had learnt the game better, I used Destiny Knot as held item for my most defensive Pokémon, so Attract now affected Miltank too. That interrupted its Rollout enough to prevent it accumulating power and always did minimal damage. That was a more successful strategy and I was tremendously proud of it.