According to Guadalcanal by Richard B. Frank, the Zuikaku had a "authorized" strength of 27 Zeroes, 27 Vals and 18 Kates. However, only 20, 23 and 20, respectively, were considered operational.
Frank states that for the first wave that launched at 0725, Zuikaku contributed 21 Vals and an unknown number of Zeroes (total 21 from all three carriers in Carrier Division One).
For the second wave launched at 0840, Zuikaku launched 16 Kates and 4 Zeroes, plus 1 additional Kate as a contact keeper for the formations.