NHL 22

You can find Ones Now under the Offline games mode menu. When selecting a character, you'll see some are grayed out and have instructions underneath what you need to do to unlock them.

There's a mascot character that unlocks just for completing a single game. You don't need to win, score, anything. Just play a game, it'll unlock the character and pop the achievement.

It will also net you the King of the Couch achievement, so it's a nice 2-for-1.