"Metagross and all Tapu in Heavy Ball discovered to be illegal"

Recently SciresM (link in the comments) decompiled the formula for Heavy Ball. It's not a multiplier, but actually adds or substracts to the Pokémon's base catch rate. The formula substracts 20 to the Pokémon's base catch rate if it's weight is under 100 Kg. All Tapu and Beldum's weights are under 100 Kg and they have a catch rate of 3, which converts to -17 under the effect of a Heavy Ball. As the formula corrects to 0 if the value is negative, the catch rate for Beldum and the four Tapu is effectively 0 if a Heavy Ball is used.Other Pokémon are affected by this, like the legendary bird trio; but none of them are in the wild in Sun/Moon, although they may be in a future game.In regards to breeding Beldum from past generations: HG/SS are the only other games where Johto Balls are available, however Beldum in those games is only obtainable in the new Safari Zone, and thus they can be caught only in Safari Balls. via /r/pokemon http://ift.tt/2n2EH4l