He will appear as the 6th Sticker in the Chibi Edition Pack.

Specialite Agent Shadow

That's Shadow "Rely", upgraded into his Soldier Grandeur form.
He was trapped by Memorial Infinite inside Fiercy Forces Game and later saved by
Silent "The Player".
He joined "Night Resistance" to stop Dr. Golden "Preparation" from invading
Silent's "The Player" and Shadow's "Rely" Real World, aka.
Sonic Forces "Different Dimension".

There are 2 Shadow the Hedgehogs in FNaS: Fiercy Forces.

Specialite Agent Shadow (Original, True) - Night Resistance

Top Stellar Shadow (Clone, Fake) - Evil Empire