Tested this because I was bored. I made a bronzong with each ability, and both floated. I also tested a snorlax with levitate and it crashed to the ground normally. I also tested a heavy metal jaroda and light metal milotic since I had normal ones on hand and knew that milotic crashes while jaroda just lands, and jaroda is close to half milotcs weight. Dispite the abilities, jaroda still landed as normal and milotic crashed. With this I can conclude that the effect depends on the species and not the ability.