This deck is straightforward but effective - Brock's Golem is easy to get to with Brock's Training Method, and with 4x Double Colorless Energies and 4x Recycle Energies, the energy ramp up happens pretty quickly since most/all of that evolution string uses colorless.
Rocket's Minefield (hopefully) sprinkles more damage onto your opponent's Pokemon as they play them, to be more susceptible to Brock's Golem's Rockslide attack, and Fissure is ready to punch heavier single-target damage if needed as well.