Voted for the clauses, more specifically Evasion first then if I could've OHKO and species. They were staples that carried over from the previous generations, were they not? Without testing them how detrimental can we say they are on the current metagame, if someone wants to rely on luck why not let them try? People use paraflinch sets on Togekiss and the like very often, and its effective use boils down to luck; as it is I've read a few warstories where at one point it came down to breaking a stalemate via a well-timed crit, that is inofitself very much luck-based. (I myself had that situation in UU, Cursemuk v. Bulktop. I got a crit and won through his upped def.)
Given the nature of Pokemon, luck is bound to be a factor; whether it's a lucky ice beam freeze or a miss on a crucial Megahorn for the OHKO, there's no escaping luck. Even were we to make every move 100% and remove all additional effects, there would STILL be chance in the form of how damage is done. Some are luckier than others and like to rely on that luck, so why not let them try their hand?
Moves like Mud-Slap are allowed, so why not Double Team? All DT does is give a turn for a counter to switch-in, and with only one evasion level it would be no worse than say Brightpowder on Mamoswine. (Although I'd have to admit, sand veil/snow cloak activate + BP + DT would cause a headache... worst case scenario on that would be Garchomp, but he's already got other moves more worthy of his time...) Not to mention a hazer/phazer could counter that stuff as easily as it counters any other stat-boosting pokemon, only easier since the evasion pokemon hasn't done anything to their offensive capabilities, and likewise can't threaten the hazer/phazer any more than that pokemon usually does...