Freddy is unlocked by getting the Bulls On Parade[ihrb.wikia.com] achievement. To unlock it, you need to kill a Werebull[ihrb.wikia.com]. They are a common occurrence in the first world, so Freddy can be unlocked fairly early on in the game. He is unlocked alongside the Broken Jetpack.

The easiest way to kill the Bull: keep note of his indicator, and when he is close enough to you, use an Ultimate attack to take him out in the easiest way. Serious Sam's and Dumpster Dave's work the best. Killing him with a Shield power-up does not count towards the achievement.

If you wish to read more about Fast Finger ready check the wiki page http://ihrb.wikia.com/wiki/Fast_Finger_Freddy