Dumb question

[ReeNormies]

(...) I pity the person who accidently triggers this encounter without being prepared, though...

You don't say... Given I personally am not yet interested in those two and will probably go after them if they're the last two 'mons missing in the dex, triggering the event by accident is what I'm most afraid of, regardless of the low chance to do so...

Why are you so afraid of the event? You can keep trying until you catch one, it will only happen if you have at least two able Pokemon in your party, your party will be fully healed when it starts, you can use the escape rope to leave it early, and if you get KOed you are already in the Pokemon center.

¯\_(ツ)_/¯