Flygon d with techs (or it's called R-gon, omaR-gon, Flu, Flytech, Florida gon etc). It has no auto-losses and has good match-ups against most decks in the format.
1. mew* and/or latios ex d- arcy, lugia, banette
2. eggs- steelix, shiftry
3. ray ex d- beldum d based decks
4. mew d POP5 against fire weak pokes-gross d, steelix, scizor
5. Early flygon ex d against a weak destiny player (a good destiny player can beat most decks, I think).
It's only weak matchup is perhaps against metanite with both latios* and lugia (and they set up 2 quick draggy d).