Underground:

shell #0
yoshi #4
1fly? #9
2fly? #8
3fly? #7

stun shell
spawn koopa in #6

spawn throwblock in #5

stun throwblock (#5)
kill koopa(#6)

spawn 4fly? in #6
spawn 5fly? in #3

spawn throwblock in #2
despawn throwblock (#5)

despawn 1fly? (#9)
despawn 2fly? (#8)
spawn 6fly? in #9

spawn 1fly? in #8
despawn throwblock (#2)

despawn 6fly? (#9)
spawn throwblock in #9

spawn 6fly? in #5
despawn 6fly? (#5) with stuntimer != 0

spawn stunned fly? in #5
spawn Unknown(FA) in #2