You must use information gained from using Pokemon Attacks and by similarities and differences from a pokemon you guess to work out which is the secret pokemon!
You play by first picking a Partner Pokemon! This pokemon will come with a helpful move to use. You can click the move to use it. The effectiveness of the move will be displayed next to the move you have just used.
We can see in this example picture of using Fire Blast that that secret Pokemon double resisted the move. We should make guesses for Pokemon of types which resist Fire in this case.
There is a search bar you can use to guess the secret pokemon. Once you guess, more information will be revealed. Don't worry about spelling the Pokemon name, the search bar will display help you. Then click "Try" to guess.
At the bottom of the page - you can see all the guesses you have made so far.
As we guess more pokemon we reveal more information. From guessing Kingdra we found out the Pokemon is also a water pokemon. We also found out that Kingdra is taller and heavier than the secret Pokemon
From the information at hand - we could guess that it is another Water Pokemon that also has a second type (in order to resist Fire Blast), like rock! Maybe a pokemon like Omastar or Kabuto. Your turn