TLDR; You might be used to using Vaporeon against Fire types. But you can actually dominate them with Rock/Water dual types:
Just like Vaporeon, Omastar’s ideal move set is:
- Water Gun
- Hydro Pump
And just like Vaporeon, Omastar is a Water type that resists Fire.
But, Omastar has a second resistance with Rock. So fire moves only do 0.64x damage.
This makes Omastar the best type counter to any Fire type.
Like Omastar, Kabutops is a Rock/Water dual type with stacked resistance to Fire.
Kabutops ideal move set is:
- Mud Shot
- Stone Edge
While Kabutops is not as awesome as Omastar against Fire types, Kabutops is a great type counter to Charizard.
- 25.8: Stone Edge has impressive DPS
- 1.25x: Stone Edge benefits from STAB
- 1.25x: Rock does bonus type damage against Fire
- 1.25x: Rock also does bonus type damage against Flying
When you combine all the damage and resistance bonuses, you end up with one of the best type advantages in the game.
Technically, Golem has two Rock moves and has an even stronger type advantage against Charizard. But I prefer Kabutops because it works well against all Fire types (and Lapras too!).