Only being good in some matchups is fine if it’s incredibly good in those matchups. Plenty of decks run cards that aren’t used in some matchups but great in others. That’s the entire basis of both “box” decks and wall decks, you use a variety of cards for a variety of decks you’ll play against.

oneshots teal mask, oneshots dengo with a bangle attached

that is incredible for a single prize basic pokemon that requires zero energy acceleration to use