Chance is per individual Starmie attack. 
mild:		0-19 spD                 20+ spD		
  0/1 def    ALWAYS SWIFT		   ALWAYS SWIFT		
 2-21 def    2/512 WP (~0.39%)     ALWAYS SWIFT,				
  22+ def   17/512 WP (~3.32%)     1/512 WP	(~0.195%)

modest:     0-19 spD                20+ spD
 0-11 def 	17/512 WP (~3.32%)     1/512 WP	(~0.195%)
12-26 def   87/512 WP (~16.99%)    8/512 WP (~1.56%)
  27+ def  256/512 WP (50%)       85/512 WP (~16.6%)

rash:       0- 4 spD               5-14 spD                   15+ spD
 0-11 def  256/512 WP (50%)       94/512 WP (~18.36%)        17/512 WP (~3.32%) 
12-26 def  418/512 WP (~81.6%)   256/512 WP (50%)            87/512 WP (~16.99%)
  27+ def  495/512 WP (~96.7%)   425/512 WP (~83%)          256/512 WP (50%)

If fought josh in moon all (normal!) defenses shunt down one (i.e. for 2 iv use the 1 iv numbers- for 0 iv still use 0 iv as 0 iv josh gets the same as 0 iv standard).


Strats 
Normal Strats: (Only Persim if Starmie >=50% chance to WP each turn).
Mild: skip persim 
Modest: get persim with 0-19 special defense and 27+ defense (28+ defense if youngster josh)
Rash: 
 0-4 spD - Always get persim 
5-14 spD - get persim with 12+ defense (13+ if youngster josh)
15+  spD - get persim with 27+ defense (28+ if youngster josh) 


Semi-Fraidy Cat Strats: (Get for staryu + >15% chance of Starmie WP per turn + conceivable use from bag if confused on Sabrina)
Mild: skip persim 
Modest:
0-19 spD - get persim with 12+ defense (13+ if youngster josh)
 20+ spD - get persim with 27+ defense (28+ if youngster josh)
Rash:
0-14 spD - get persim 
 15+ spD - get persim with 12+ defense (13+ if youngster josh)
 

Fraidy Cat Strats: (Get for staryu + use from bag on sabrina)
Get Persim (-1+ if youngster josh)