Tyranitar is weak to Fighting, Bug, Fairy, Grass, Ground, Steel, and Water moves, with a double weakness to Fighting.

Typing and core weakness

  • Tyranitar is a dual Rock/Dark type, so type effectiveness stacks.
  • Because Fighting is super effective on both Rock and Dark, Tyranitar takes 4× damage from Fighting moves, making this its most dangerous weakness.

Full list of weaknesses

  • 4× weakness: Fighting (Machamp, Lucario, Iron Valiant, etc. hit extremely hard).
  • 2× weaknesses: Bug, Fairy, Grass, Ground, Steel, Water (common attacking types in most formats).

Useful resistances to remember

  • Tyranitar resists or double-resists Psychic and several others, which is why it’s popular into Psychic and Ghost types despite its many weaknesses.
  • In formats like Pokémon GO and competitive singles/doubles, it often shines when protected from strong Fighting- and Water-type attackers.

Quick battle tips

  • Lead or pivot in Fighting types to delete Tyranitar quickly; even neutral-attackers struggle compared to a proper Fighting STAB.
  • If Fighting coverage is unavailable, lean on Water, Ground, or Fairy moves, which are widely distributed and still hit it super effectively.

TL;DR: Tyranitar’s many weaknesses are Fighting, Bug, Fairy, Grass, Ground, Steel, and Water, and Fighting is by far the most important one to exploit.

Information gathered from public forums or data available on the internet and portrayed here.