>>32578710Felt I could do it on level 10.
Brock had a Horsea and a Shellder. Celeste took care of the former spamming Wrap but had to cycle through the team to weaken the latter so Lisa the Butterfree could Confusion it down.
On to Mt. Moon. Will have 4 new mons when I get to Cerulean: routes 3, 4, Mt. Moon and the Magikarp seller - I won't count gift/bought mons as part of the area, since that's why I'm playing Yellow not RB).