Hm... I still think Vaida wins if you allow her to equip a Spear and counter magic with it. Joker's damage, even if doubled due to he 49% average res, is still 94% to just over average HP, and I can't see him doing any more (and it's a subtractive system in FE, so it should do a little less). His slow-ass charge time (65% of average) means that he's neither going first nor doubling if he uses Explosion, and Blazing Wall doesn't double either so it's a waste. Physicals blow against Vaida, as usual.
So, Vaida goes first, chucks a Spear. Joker hits her with Explosion, she narrowly survives to counter. Then, her turn comes again, and she kills Joker, as he's below average on HP and defense, and she's got slightly above average damage with a spear (if you take doubles and/or counters into the average, she's screwed, and I think some people here do?).
Granted, I haven't looked at her accuracy against his evasion which could uh... blow this whole thing right out of the water. You also have to see damage averages for both, Suiko charge times, FE defenses, and FE counters all from the same (I don't think too unreasonable or uncommon) point of view, but that's how I'm seeing it, unless someone gives me really low hit rates from Vaida against Joker with a Spear.
Also, sorry if I missed something blatantly obvious and/or made a point from a POV that I thought people held that really only I see things from.
