How do you get baulbasaur in yellow version Kanto?

Answer 1

Your Pikachu has to be happy. when you talk to it, it should have a smiley face or hearts.

One easy way to do this:

Make sure pikachu is in full health.

get a potion and use it on pikachu 10 times( note it will not heal because it is in full health but just do it!)

Talk to the lady in cerulean city and you got yourself a healthy level 10 bulbasaur!