The improved Will-O-Wisp is exactly why it's better.
Also, one more thing. Grasswhistle passes through subs now, making Whimsicott and ChloroSaur even better.
Same for mons with sing, i.e chansey etc. Also you do realize that zweilous has
**** SpA for Draco Meteor, in no way it is it going to be a wallbreaker, as bulky physical walls can still take care of it.