Where are the best locations to find each Pokemon in FRLG?

Question

"best" being defined as:
- Highest encounter rate
- Closest level to evolution level
or, both of the above.

I'd like a comprehensive list as I'm looking for a living dex and would like to see the best places to catch Pokemon for the task, as I'm finding it irritating checking through every single route and ever single Pokemon Page.

I understand this is a large question, and therefore I shall contribute to this as well as I come across them.

Comments

caterpie/metapod: pattern bush (close to evolution level 15% encounter rate FR, 30% lg), viridian forest (45fr 50lg encounter rate)
pikachu: power plant (highest encounter rate at 25%)
raichu: evolution only
Jigglypuff: Route 3 at 10%
Wigglytuff: evolution only
magneton: cerulian cave at 20%
parasect: cerulean cave at 25%