The next egg to be generated by the game has a set inheritance and can be abused by resetting and inputting the correct parents into the daycare for a specific spread (physical attacker, special attacker, trick room, hidden power, etc.)Whats a Time Machine spread? :p
http://www.smogon.com/forums/threads/some-sort-of-egg-rng-abuse-read-the-first-post.3491324/