Autotomize lowers the user's weight by 220 lb, so what happens if a Pokémon less than 220 lb uses it?
Autotomize succeeds at increasing the user's speed regardless of its weight, unless it is already at +6. The move's secondary weight change effect works in the following manner:
Autotomize raises the user's Speed stat by two stages and (if the user successfully changes its Speed) decreases its weight by 220 lbs. (100 kg). If the user successfully changes its weight, the message "[Pokémon] became nimble!" is displayed. Autotomize cannot decrease the user's weight below the minimum 0.2 lbs (0.1 kg); if the user's weight would drop below the minimum, it becomes the minimum instead. Weight loss from Autotomize stacks, so using it multiple times will continue decrease the user's weight accordingly until it reaches the minimum weight.
Autotomize raises the user's Speed stat by two stages and (if the user successfully changes its Speed) decreases its weight by 220 lbs. (100 kg). If the user successfully changes its weight, the message "[Pokémon] became nimble!" is displayed.
Autotomize cannot decrease the user's weight below the minimum 0.2 lbs (0.1 kg); if the user's weight would drop below the minimum, it becomes the minimum instead. Weight loss from Autotomize stacks, so using it multiple times will continue decrease the user's weight accordingly until it reaches the minimum weight.
source Float stone is the thing that halves weight.
automize actually takes your weight and divides it by 2, thus halving your weight. It also raises speed by 2 stages. it doesnt actually lower the users weight by 220.