Some instructions are in-game. WSAD to move Scyther, arrow keys to move Beedrill. Each time you use Agility or Quick Attack, Scyther gets faster.
I changed it so then when the Pokemon faint, they go back to full HP. If you want Scyther and Beedrill's speed to be equal, use Agility 11 times. I also added the "H" in Scyther's controls.