I gathered this in training mode... rather quickly actually. BK was way easier than Joker or Hero thanks to not having any particularly unusual mechanics to deal with. These are just the "hits on" frames for all of their basic attacks which should give you a general sense of which moves are your relatively fast/slow options. BK seem a bit slower than a typical character but not crazy slow or anything. Charge release on the smashes refers to on which frame you hit after letting a charging smash loose, and yeah, that f3 charge release on usmash is kinda outlier fast; I checked it like 5 times to make sure I wasn't crazy.
jab: 4
ftilt: 7
utilt: 11
dtilt: 12
dash attack: 9
fsmash: 19 (10 charge release)
usmash: 9 (3 charge release)
dsmash: 13 (11 charge release)
nair: 10
fair: 15
bair: 8
uair: 7
dair: 15
standing grab: 7
running grab: 10
pivot grab: 11
Neutral-B (normal stance): 13
Neutral-B (Kazooie held): 4
Side-B: 18
Up-B: 20 (falling spring pad)
Down-B: 10
Note: Side-B goes invincible on the frame it hits (f18), but being hit out of the start-up will not consume a golden feather.
Note2: You cannot attack out of up-B until the being launched animation finishes which happens at the peak of the jump. There is no OoS attack via up-B vaguely available.
jab: 4
ftilt: 7
utilt: 11
dtilt: 12
dash attack: 9
fsmash: 19 (10 charge release)
usmash: 9 (3 charge release)
dsmash: 13 (11 charge release)
nair: 10
fair: 15
bair: 8
uair: 7
dair: 15
standing grab: 7
running grab: 10
pivot grab: 11
Neutral-B (normal stance): 13
Neutral-B (Kazooie held): 4
Side-B: 18
Up-B: 20 (falling spring pad)
Down-B: 10
Note: Side-B goes invincible on the frame it hits (f18), but being hit out of the start-up will not consume a golden feather.
Note2: You cannot attack out of up-B until the being launched animation finishes which happens at the peak of the jump. There is no OoS attack via up-B vaguely available.