It's also possible to make Gen I unwinnable if you release all your Pokémon in Cinnabar (except for one, who can't learn surf or fly) and then get rid of all your money and Pokéballs so that you can't catch any Pokémon. You have to pretty much be trying to do this, though. But back when you could actually rent Game Boy games, it wasn't uncommon to find the pre-saved file trapped in some place like Cinnabar with no way to catch Pokémon.
It wasn't uncommon? Then I wonder how many people actually got trolled by this.