相あい手てを選えらぶ

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).

• 彼かれは喧けん嘩かをするとき、相あい手てを選えらぶ。

  He picks his opponents when he fights.

• あの詐さ欺ぎ師しは相あい手てを選えらばない。

  That con artist doesn't discriminate between targets.