[user 18]

Okay, QWAZ, take a Charmander as your starter.

When you start your adventure, Charmander can only use moves with a max BP of 40.
Every level you delay evolution to Charmeleon by will increase this limit by 5.
Every level you delay evolution to Charizard by will increase this limit by 5.
Every gym in which you solo all of the trainers without leaving the gym will increase your limit based on which gym:

Pewter: 10
Cerulean: 20
Vermilion: 5
Celadon: 5
Saffron: 15
Fuchisa: 15
Cinnabar: 10
Viridian (as Charmander/Charmeleon): 20
Viridian (as Charizard): 10

Evolution can be delayed by a maximum of four levels per evolution. For example you can delay evolution to Charmeleon by four levels, and evolution to Charizard by four levels, but you cannot delay evolution to Charmeleon by 6 levels. All other power increases must come from beating gym trainers.