Don't worry about it.
Sorry for lack of info on Ditto, nature escaped me completely.
I guess I would want it to be Jolly, and Japanese I hear is better for shiny.
For Marshadow, I would like the following:
Marshadow @ Life Orb
Ability: Technician
Level: 50
Nature: Jolly
Shiny: N
EVs: 4 HP/252 Att/252 Spe
IVs: 0 SpAtk
Move 1: Spectral Thief
Move 2: Close Combat
Move 3: Shadow Sneak
Move 4: Ice Punch
Pokeball: Moon Ball (if possible)
Thanks again.