As mentioned by other posters all MLL in YYZ have showers. The domestic ones are located in the back near the BMW TV room.
I don't believe they have an iron (fire hazard), however I have found de wrinkle spray (that you can buy at the grocery store) to be pretty good for de wrinkling clothes when I travel.
Failing that, leave your suit in the shower room while you shower. That should get rid of any serious wrinkles.