With Virizion's Leaf Wallop attack does it continue to go up by 40?
for EX. The first time I use it, it does 40, then 80, after that would it do 120? then 160? If not, how would it work?
No, the first time you use it, it does 40. The next turn, it does 80. The next turn after that, it does 80. It's because it's adding 40 to the base damage of the attack, which is 40.