Politoed could only use Dive.
 

The Politoed I was using had Bubble Beam, Attract, Dive and Seismic Toss.

Maybe this isn't a bug, however, this is the Smogon University; maybe you know the anwer.

I'm guessing (and hoping from the bottom of my soul...) that this was Challenge Cup and it was holding a Choice item, but you weren't aware due to, well, it being CC.

What would look stupider;

me not knowing because it was a Challenge Cup,

or me not knowing because that was a Pokemon I built.

Glad you figured this out. Even if this were a bug, though, you'd want to post this to the Pokemon Online forums, not here.