Not all knuckleballs are alike, but for fun, 3 hitters have had over 20 PAs v. Wakefield - Pudge, Guz, and Kennedy.
Pudge: 54 PAs, .286 /.333 / .490
kennedy: 30 PAs, .241 /.267 / .379
Guzman: 23 PAs, .286 / .348 / .571
Kennedy has done better against Dickey (16 PAs, .267 / .333 / .533), with Guz 0 for 5, but IIRC Dickey has not always been a knuckleball pitcher. He came up with Texas, and I think did not throw significant MLB innings with using a knuckleball until he was with Seattle. Kennedy's ABs were probably in 2003 and 2004, pre-knuckleball, I think, w/o further checking.