expression, godan verb (-bu)
choose one's opponent/partner; pick one's battles; discriminate between targets
Literally 'choose one's opponent/partner'. Used when someone is selective about who they deal with, fight, or target. The 'discriminate' nuance often appears in negative contexts (e.g., criminals not choosing victims).
彼は喧嘩をするとき、相手を選ぶ。
He picks his opponents when he fights.
あの詐欺師は相手
That con artist doesn't discriminate between targets.