Some kid traded me his shiny Melmetal from LGPE to SwSh but he replaced toxic with Acid Armor and superpower with Body Press. Would the move toxic have made a major difference?
Double battles are generally shorter, so status moves like toxic, acid armor, and skill swap are less useful. Melmetal wants strong attacks like double iron bash, thunder punch, high horsepower, or body press. Its only good status move is protect.