Chuck's shadow extended out as the dark aura seemed to flow out of him and into his shadow.  And, as Shiranui had guessed, Marshadow appeared out of the shadow.  However, he was not alone.  Soon after Marshadow had surfaced, another figure began coming out of his shadow.  This man was clad in all black, with a white mask covering his face.  The man cracked his neck as the shadow separated from Chuck, who got to his feet, winded but otherwise ok.  "I'm afraid I can't let you progress any further." this Masked Shadow said.  "The poachers have gathered a fair amount of Pokémon, free for the shadows and I can't allow you to free them, nor can I allow you to stop Necrozma from taking this world's light.  Without light, my Shadows can roam free."  Out of his cloak he produced two Dusk Balls and tossed them.  Out came a Rampardos and a Bastiodon, however these were radiating a dark aura.

(think Shadow Pokémon from Coliseum)