Yes, the name sounds like an oxymoron. It'll make sense, I promise.
The basic premise is you play a randomized copy of a Pokemon game with the goal of completing the Pokedex, acquiring the Diploma/Certificate for doing so, and then defeat the strongest trainer(s) the game has to offer in story. The snag is that Pokemon must be acquired in a fixed order, creating interesting limitations on team building and progression. Randomization is used to ensure each playthrough presents a different set of obstacles and challenges, as well as ensuring all Pokemon are obtainable.
The goal of this challenge is to offer a playthrough model that is not strictly oriented around increasing difficulty through self-imposed rules (Nuzlocke) nor requiring insane amounts of grinding (Professor Oak), but still remaining compatible with those ideas.
The challenge is currently designed for any of the mainline games in Generations 1 through 5.
Please refer to the Wiki for all rule sets, tool links and guides.