Antialiasing usually only applies to 3D games. In Construct 2, a different technique is used: when you press crop it automatically leaves a 1px transparent border around the edge. This is not actually antialiasing, but it does help give rotated objects a "smooth" edge. Try pressing crop on any objects with sharp edges - it will add a 1px transparent border if there isn't one already.
Yea of course I crop every single image, why the hell wouldn't I for a player sprite?
And with the program I rendered it with (Blender) I set the AA to x16 and if you check the preview of the player sprite you can see its smoothness:
It's just when an animation is being played that it's not smooth.