En el siguiente ejemplo, tu personaje hace el spin dash manteniendo a mientras estas agachado.

;--------------------------------------------------------
; Spin Dash
[Statedef 620]
type = S
movetype= A
physics = N
velset = 0,0
anim = 200
ctrl = 0

[State 40, 4]
type = ChangeAnim
trigger1 = Command = "a" || Command = "b" || Command = "c"
value = 200

[State 620, Hit With Spin]
type = HitDef
trigger1 = time = 0
attr = S, SP
animtype = Medium
damage = 50
guardflag = MA
pausetime = 0,0
sparkno = S23242
;sparkxy = -10,-70
hitsound = 5,2
guardsound = 6,0
ground.type = High
ground.slidetime = 12
ground.hittime = 13
ground.velocity = -5.5
air.velocity = -2.5,-4
air.fall = 1
fall = 1
ground.cornerpush.veloff = -20 ;To push far away when p2 is in corner

[State 620, Dash Snd] ; sonido
type = PlaySnd
trigger1 = time = 0
trigger2 = Command = "a" || Command = "b" || Command = "c"
value = 7,0

[State 620, Break Dust] ; efecto de tierra levantandoce
type = Explod
triggerall = pos y = 0
triggerall = numexplod(620)!= 1
trigger1 = time >= 0
anim = 600
pos = -7,0
sprpriority = 3
bindtime = -1
removetime = -1
ownpal = 1
id = 620

[State 600, Go to Rolling Spin]
type = ChangeState
trigger1 = command != "holddown"
trigger1 = time >= 5
value = 621
ctrl = 0

;---------------------------------------------------------------------------
; Rolling Spin
[Statedef 621]
type = S
movetype= A
physics = N
anim = 43
ctrl = 0

[State 621, Dash Snd End]
type = PlaySnd
trigger1 = time = 4
value = 7,5
channel = 0

[State 621, 1] ;Gravity
type = VelSet
trigger1 = 1
y = 0

[State 621, 1] ;Gravity
type = VelSet
trigger1 = time = 0
x = 14

[State 621, 1]
type = Veladd
trigger1 = 1
x = -0.5 ; mientras mas grande sea este valor, mas rapido se frena
ignorehitpause = 1

[State 621, End]
type = ChangeState
triggerall = time >= 30
trigger1 = vel x <= 1
trigger2 = frontedgedist <= 5
value = 0
ctrl = 1

;---------------------------------------------------------------------------

ESo es todo, ese codigo no usa variables ni nada raro, es sencillo y fasil, solo le tenes que configurar las velocidades y las animaciones y sonidos. Cualquier problema me avisas.

En este ejemplo se hace solo con el boton C (pero no se puede cargar, porque cuando sueltas el boton C para volver a apretarlo el personaje sale disparado)

;--------------------------------------------------------
; Spin Dash
[Statedef 620]
type = S ; no cambiar
movetype= A ; no cambiar
physics = N ; no cambiar
velset = 0,0
anim = 200
ctrl = 0

[State 40, 4]
type = ChangeAnim
trigger1 = Command = "c"
value = 200

[State 620, Hit With Spin]
type = HitDef
trigger1 = time = 0
attr = S, SP
animtype = Medium
damage = 50
guardflag = MA
pausetime = 0,0
sparkno = S23242
;sparkxy = -10,-70
hitsound = 5,2
guardsound = 6,0
ground.type = High
ground.slidetime = 12
ground.hittime = 13
ground.velocity = -5.5
air.velocity = -2.5,-4
air.fall = 1
fall = 1
guard.dist= 0
ground.cornerpush.veloff = -20 ;To push far away when p2 is in corner

[State 620, Dash Snd] ; sonido
type = PlaySnd
trigger1 = time = 0
trigger2 = Command = "c"
value = 7,0

[State 620, Break Dust] ; efecto de tierra levantandoce
type = Explod
triggerall = pos y = 0
triggerall = numexplod(620)!= 1
trigger1 = time >= 0
anim = 600
pos = -7,0
sprpriority = 3
bindtime = -1
removetime = -1
ownpal = 1
id = 620

[State 600, Go to Rolling Spin]
type = ChangeState
trigger1 = command != "hold_c" ; tienes que crear este comando.
trigger1 = time >= 5
value = 621
ctrl = 0

;---------------------------------------------------------------------------
; Rolling Spin
[Statedef 621]
type = S
movetype= A
physics = N
anim = 43
ctrl = 0

[State 621, Dash Snd End]
type = PlaySnd
trigger1 = time = 4
value = 7,5
channel = 0

[State 621, 1] ;Gravity
type = VelSet
trigger1 = 1
y = 0

[State 621, 1] ;Gravity
type = VelSet
trigger1 = time = 0
x = 14

[State 621, 1]
type = Veladd
trigger1 = 1
x = -0.5 ; mientras mas grande sea este valor, mas rapido se frena
ignorehitpause = 1

[State 621, End]
type = ChangeState
triggerall = time >= 30
trigger1 = vel x <= 1
trigger2 = frontedgedist <= 5
value = 0
ctrl = 1

;---------------------------------------------------------------------------

Y para que se realice el ataque, en el archibo CMD tienes que agregar el siguiente comando:

[Command]
name = "hold_c"
command = /c
time = 1

y tambien en el CMD, mas abajo, en el statedef -1, agregas esto:

;spin dash
[state -1]
type = changestate
value = 620
triggerall = command = "hold_c"
trigger1 = ctrl
trigger1 = statetype != A

Eso es todo, para mas dudas o problemas me avisas, porque este codigo no está probado...

Lo del explod que no se elimina, arreglalo y dejalo así:

[State 620, Break Dust] ; efecto de tierra levantandoce
type = Explod
triggerall = pos y = 0
triggerall = numexplod(620)!= 1
trigger1 = time >= 0
anim = 600
pos = -7,0
sprpriority = 3
bindtime = 1
removetime = -2
ownpal = 1
id = 620