It's early FFT so Priest's MP is going to SUCK, and thanks to Speed(?), Bowser is going before Deis2, and therefore won't benefit from ATK Up until his second turn. THAT SAID...
It might not make a whole lot of difference, but Bowser isn't faster than Deis2 even with Speed?. Deis2 is something like 170% average speed so even with the 5% reductions she's still easily faster than Bowser's 120%.
170% average speed doesn't mean much when it's in a TB system. If you take SDs into account, she's... Still faster, yeah, with +1.54 SDs above average, though that's knocked down to +1.46 (~136% if 1 SD = 25%) after the Speed? debuff. So yeah, she is faster. Not quite as blindingly fast as 170%, but still. Please excuse my earlier incorrect assumption.