At first, my brain switched the letters in "Ariados" so I pronounced it uh-RY-dos. Then there's Dusknoir and Gardevoir, which I used to pronounce Dusk-NWAH and Gar-duh-VWAH, but now I say them Dusk-NOR and Gar-duh-VOR. Of course, there was a time when I said Dusk-NOY-er, which is even worse. I still don't know how to pronounce those two.
With Xatu I sometimes try to pronounce the X as an X, so it comes out "KSATU." Other times I say "ZATU".
Suicune has always been a challenge for me, so I just say it the way it's spelled: SOO-i-coon.