The Base Power of Return is calculated like this: Happiness/2.5. A base Happiness of 150 would be 60. A base Happiness of 199 would be 79.6(rounds down to 79) EDIT: The power would therefore be between 60 and 79 if the Happiness was between 150 and 199. Max power of Return is 102 at 255 Happiness. Source:http://www.serebii.net/games/returnfrust.shtml