FFFFFFFFFFF- YES

SO. Dig this. Turns out that you can access Route 18 as soon as you get Surf (that is, right after Gym #6).

In a house on Route 18 is a man who gives you the egg of a certain PokeMon.

..... TL;DR. PRE-ELITE FOUR SUN-MOTH, BITCHCAAAAAAAAAAAAAAKES~!