bee41638_Phanpy___Pokedex___Marriland__Power
[Egg] Egg [Name] Heavy Slam [Type] Steel [Category] Physical [Acc %] 100% [PP] 10 [Target] One Nearby [Power] 
Heavy Slam's power is greater depending on how much heavier the user's weight is compared to the target Pokémon's weight (according to the Pokedex), with a maximum of 120 power if the user weighs 5x as much as the target.varies
Phanpy - Pokedex - Marriland
Power