Combat simulation system in the gym in 100 seconds.Using the Dueling ability to compare.When selected defender pokemon, system will automatically choose the best defense.
About these values
Originally got our data from Professor_Kukui is Species Data table (here), but because he did not updated it for pokemon generation 2 . I copied his spreadsheet and now I update it ourselves. He used the terms "Dueling Ability" , "Gym Offense" and "Gym Defense". You can find the details on his table.
Damage =Floor(0.5*Power*(Attack/Defense)* STAB * Weakness)+1 (TheSilphRoad)
Weather Types will be more effective in battle (by around 20%)