Sadly, this is what teams actually looked like in Gen 1.
Why is this sad?
wait did gengar seriously run mega drain
Rhydon and Golem are common switches to take the Explosions/Thunderbolts. Mega Drain is the only way for Gengar to beat them, aside from putting them to Sleep (which is risky considering that the accuracy isn't the greatest and if he misses then an Earthquake will easily dispatch him.