a signature move or finishing technique (especially of a fighter, wrestler, etc.); a move someone is particularly good at.
彼の得意技は関節技だ。
His signature move is a joint lock.
相手の得意技を研究して対策を立てた。
We studied the opponent's signature moves and prepared countermeasures.
子どもたちは遊ぶときにそれぞれの得意技を披露した。
When they played, the children showed off each of their favorite moves.