According to the search results, Golem is a Rock/Ground type Pokémon in Pokemon Go, which makes it especially weak against Water and Grass moves, and weak against Fighting, Ground, Steel, and Ice moves. Therefore, the best ways to defeat Golem in Pokemon Go are to use Pokémon with moves that exploit its weaknesses. Some of the strongest Pokémon to use against Golem include:

• Primal Kyogre
• Mega Swampert
• Mega Sceptile
• Kartana
• Mega Blastoise
• Kingler
• Zarude
• Roserade
• Rillaboom

It is also important to choose Pokémon with equal or higher CP than that of the Golem you are battling, and to use move types that Golem is weak against.