From Pokemon World Online Wiki
Return inflicts damage and has no secondary effect. The base power of Return is dependent on the friendship of the user. The greater the user's friendship, the greater the base power. The base power can be calculated using the following formula:
The base power of Return varies between 1 (at the minimum friendship value of 0) and 102 (at the maximum friendship value of 255). The base power of Return is set to 1 if the formula outputs 0.
|Pokémon that learn it via level-up:|