We've always knew what it looked like.
But speaking of whom, the event Marshadow's moves have been confirmed:
Spectral Thief (Obviously, Signature move and needs it for its Z-Move. Plus its a pretty good move)
Close Combat (Great! That pretty much covers its STABs, now they can focus on coverage or utility)
Force Palm (Er, okay, I mean I guess its nice to have a Fighting-type option that doesn't have a negative effect but there's better options)
Shadow Ball (... it's a physical attacker. Yes, it's Special Attack is okay, but any competitive ones will have either an Adamant or Jolly Nature)
And it's not like Marshadow is suffering in movepool options. It gets the elemental punches, Drain Punch, Shadow Sneak, Jump Kick, and Sucker Punch (actually, Shadow Ball isn't even a level-up move! With TMs as options there's Acrobatics, Stone Edge, Rock Slide, & Poison Jab).
Well, it's no big deal, you'll just have to give it the right moves.