As we have seen here https://abn397.wordpress.com/2019/10/20/umesh-yadavs-batting-record/
The fastest score of 25+ was 31/10 balls, with a strike rate of 310.00
For 50+, it is 54/25 balls and 216.00
For 100+, it is 110*/58 balls and 189.65
Now let use see about the highest strike rates for innings lasting for one to six balls.
There is no record of anyone scoring more than a zero off zero balls, though it may be theoretically possible under some obscure rule.
Here you have only 0* and 0, the latter being diamond ducks.
Now for 1-ball innings:
There is only one such innings involving a six, and it is fittingly by Jayasuriya with an SR of 600. Next is Ishant Sharma with 5 (a single plus 4 overthrows) and 500. Then there are those who scored a 4 or 3 off one ball. Ishant Sharma appears again. At least half of the batsmen here are tailenders. Even the famous batsman CS Martin has scored 4 off one ball! So has NM Lyon.
There are four batsmen (all tailenders) who have made 7 off two balls. They would have made a 6 and a single, apart from Muralitharan who made a 4 and a 3. Then there are 6s and 5s. Here we do not meet a recognized batsman until Sir Richard Hadlee (?) and AL Logie. The only current players are Wafadar of Afghanistan and India’s Mohammed Shami.
The highest off 3 balls is 12* by Misbah, including two sixes and a dot. Murali has 6,4 and dot while Shami has two fours and a two. Others have made 6 runs with one four. Muralitharan appears three times here. The proportion of recognized batsmen is more here, including current players Mushfiqur and Malan along with Shami.
The maximum here is 12, either by 3 fours (de Villiers and Warner) or 2 sixes (Henry). Warner, Henry and M Marsh represent the current players.
The best here is by Southee (another expert tailend slogger) with 3 sixes in his 20. He has also made 13 to be in second place with Pietersen.
The highest here is 17* which is less than the 20 in 5 balls. Ntini made his 16* with 4 fours. KMA Paul’s 12 included 3 fours.
Having come so far, we can also see
Most successive sixes:
Kapil’s 4 successive sixes came when averting the follow-on with No 11 at the other end. The No 11 (Hirwani) was out just after the follow-on was averted. There are numerous current players here (such as Southee) besides old-timers such as Hammond.
Most successive fours:
All 6 balls by Jayasuriya, Sarwan and Gayle (although Sarwan had a no-ball interspersed after 4 sixes. DW Hookes hit 5 fours on his debut, which came in the Centenary Test of 1977. So did RE Redmond, a staple of quiz questions.