Click on the Derpemon (while it's not moving) to try to catch it (pressing B also works) the more you catch, the harder it gets. If it stops moving (because you clicked too fast) just press spacebar pressing space also resets position press r to run away from a Derpemon. press the button in the top left corner to show your Derpemon. Press up to see each individual one. Press down to hide this list. If there are 2 or more Derpemon on the screen at the same time than wait a second and don't go so fast. Some Derpemon can only be caught once you've caught other Derpemon, sometimes more than 1.
Based on pokemon, duh...
