Regarding Butterflies, how many carriers did IJN intel thought the USN could deploy for the defence of Midway?
Given their tendency to claim damaged ships as sunk, they were probably counting only with two. PODs that give the USN four or five carriers possibly also allow the IJN to expect them, and have a completely new plan.
If the carrier is
Saratoga coming from the West Coast because the Midway op is delayed by a week, then you can probably allow it to be discounted by the IJN.
Saratoga would operate in division with
Yorktown - I think Fitch was still en route to Pearl so it would be Fletcher commanding.
Following Coral Sea, Fletcher would be aiming to get the division's strike aircraft over target at the same time - although that failed with Yorktown, so I'm not sure we'd be more generous to the division. What is slightly more likely is that the
Saratoga's planes would stay with
Yorktown's of the same types; so the torpedo attack would be of about thirty planes, and might actually get a hit that worked, or, more likely, have several hits observed by survivors as duds.
I don't have any books with me, but IIRC
Hiryu was not seen by the OTL SBDs, due to her maneuvering against previous air attacks having taken her away from the other carriers, and so would survive the TTL SBD strikes as well.
If that's the case, though, Yamaguchi's counterstrike will have to get through a couple more escorts and a few more CAP F4Fs. With the escorting A6Ms already engaged by
Yorktown's CAP after detection at 1329 hrs, any contribution from
Saratoga will be able to try to break up the D3A attacks, which might well mean that
Yorktown can avoid the bomb in the uptakes that slowed her to 20 kts.
With
Saratoga still undamaged, she can continue to land and refuel the CAP, including the VF-3 planes from
Yorktown, and then relaunch them so that when the second strike of Kates is detected as 1540 hrs they are engaged further out by more defenders. With more CAP and more time, and
Yorktown not slowed by bomb damage, she escapes with a single torpedo hit, which while serious is not as fatal as the two in OTL. Not all the boilers flood, power to the pumps is maintained, the flooding is controlled.
Saratoga launches her own strike against
Hiryu, although the time taken defending against
Hiryu's attacks and landing
Yorktown's planes means that it goes later than Spruance's strike, and finds
Hiryu burning and chooses different targets, damaging
Chikuma and springing hull plates on
Makigumo with a near-miss.
Fletcher retires east overnight.
I-168 never finds
Yorktown, and she is repaired fully in time for the Eastern Solomons.