@A$AP Buckus: Here is the whole piece of coding in case you want to fix your own issues with cross ups:
This goes inside statedef -2. Feel free to use any state number for the helper. Its ID is also never referenced anywhere else so you can change that here and will not need to change it anywhere else. Stateno range is the usual aerial basic attacks' range. Tweak it to add any other moves like character specific stuff for example.
[State -2]
type = helper
trigger1 = !numhelper(9392)&&movetype=A&&stateno=[600,699]
stateno = 9392
id = 9392
pos = 0,0
name = "CROSS UP FIX"
pausemovetime = 999999999
ownpal = 1
ignorehitpause = 1
And this is the helper's state itself. It's a copy-paste and forget block. You only need to change the statedef number in case you changed it in the helper sctrl from step 1, and tweak the destroyself if you added any extra states in the sctrl trigger. I used angledraw instead of an assertspecial to make the helper invisible just to avoid any rare circumstance where the assertspecial may have a 1 frame delay to get activated (Unlikely if you only use one flag but hey! Mugen!).
Of course, you may need to increase the attackdist value depending of how's your game like.
;-------------------------------------------------------------------------
; CROSS UP GLITCH FIX
;-------------------------------------------------------------------------
[Statedef 9392]
type = A
movetype = A
physics = N
sprpriority = 0
ctrl = 0
; FACE TO THE OTHER SIDE TO FIX UNBLOCKABLE CROSS UP GLITCH
[State 9502]
type = Turn
trigger1 = facing=parent,facing
[State 0, NotHitBy]
type = NotHitBy
trigger1 = 1
value = SCA
time = 99999999
ignorehitpause = 1
[State 9390]
type = Width
trigger1 = 1
value = 0,0
[State 9390]
type = PosSet
trigger1 = 1
x = ceil(parent,pos x)
y = ceil(parent,pos y)
[State 9390]
type = ScreenBound
trigger1 = 1
value = 0
movecamera = 0,0
[State 0, AngleDraw]
type = AngleDraw
trigger1 = 1
value = 1
scale = 0,0
ignorehitpause = 1
[State 0, ChangeAnim]
type = ChangeAnim
trigger1 = 1
value = parent,anim
elem = parent,animelemno(0)
ignorehitpause = 1
[State 3000000]
type = HitDef
trigger1 = 1
getpower = 0
givepower = 0
hitflag =
hitonce = 1
[State 0, AttackDist]
type = AttackDist
trigger1 = 1
value = 160
ignorehitpause = 1
[State 3000000]
type = STATETYPESET
trigger1 = parent,statetype=S
statetype = s
ignorehitpause = 1
[State 3000000]
type = STATETYPESET
trigger1 = parent,statetype=c
statetype = c
ignorehitpause = 1
[State 3000000]
type = STATETYPESET
trigger1 = parent,statetype=a
statetype = a
ignorehitpause = 1
[State 3000000]
type = destroyself
trigger1 = parent,movetype!=A||parent,stateno!=[600,699]
ignorehitpause = 1
