Yeah I sold lots of poekmons but this was pokemons like natu so I didn't give them macho brace.
Idk I fight him only against some NPC's in volcan island. I don't think so any of them used Thief, Covet, or Trick on my Chansey especcially that they only used one hit me before I defeted them. And I didn't fight many times against wild pokemons as a chansey.
If it will be helpful I used macho brace on only some pokemons like : Klefki, Blissay, Chansey, Gengar, Snorlax, Conkeldurr(it was timbur or gurdurr yet) and chinchou.