this thing it's a monster, i don't see haunter as a good answer, if u already did belly and ur opponent had haunter u can just run away and pursuit with buzz, then belly again in a predicted rest or something, sitrus berry for the win.
the best lax in the serv some time ago (tfat lvl50 before breeding), bought dat arca for 2egg (inti was bug sadly), and caught that slow in safari (otempo).