I may have read that as the inverse.
On the other hand, gasoline is not really a "poison" and the fact that most substances are qualified as poisonous doesn't really make them the classic poison sludge pokemon's POISON is all about. Most chemical substances are poisonous and pretty much everything in our world is flammable or explodes in the presence of O2, pokemon POISON is more about that weird sewage sludge which might or might not catch fire but really is something you wouldn't want to find yourself due to disease. Which bugs have no problem with, ground is unaffected and can easily absorb by and medicine (brain power-psychic [kind of a stretch]) kinda beats while plants fear it for their life.
Go to walmart with link cable, use gameboy there, trade and trade back.
Even Water type pokemons should be weak to it going by Real World logic, I mean, we can cook whales and pretty much everything that moves.