Simple is interesting, although I am having a hard time seeing any sets other that choice sets picking weak armour over simple. This could be balanced in the moveset stage, though. Including very few stat changers that would only profit from having simple (Swords Dance, Tail Glow, maybe even Quiver Dance), instead staffing it with moves like Curse and Shell Smash would make Simple less appealing.
And, while it doesn't exactly synergize with Weak Armour, Trace would be an interesting pick. While it isn't very tactically viable, it has the potential to give a hefty award with a really good ability, like Swift Swim while fighting a rain team, or Heatproof after switching in on a Heatran.
"When people think of time, they think of a straight line between cause and effect, when actually it's more like a... a big ball of... wibbly-wobbly, timey-wimey... stuff." "Time is not made of lines. It is made of circles. And that is why clocks are round."