>>57022359Okay, the most tryhard autistic answer you could possibly get coming up:
Given that this is gen 3, the best possible bet you have against Gengar (assuming they don't have Psychic like other anon said, which they probably will AND you live, which I don't even know the damage calcs on that shit don't bother just hope they don't have it) is using either Flatter and hoping for confusion hax or having beat up from an egg move with sneasel as the parent and holding Black Glasses to maximize the damage. Personally, I think the confusion hax of either flatter or swagger (probably better to take advantage of the heightened confusion damage from attack boost, but you get Flatter by level up). The best thing you could do would be to not let this situation happen in the first place or just switch. You could also use Thunder to hope for parafusion. You'll need some luck though no matter what.