Grand League Boss Stages MAJOR SPOILERS

Cluster Prime Core (Jenny Wakeman v. Madara Uchiha)

Ruined Hall of Origin (Legendary Pokemon v. Sasuke Uchiha)

Kokuō's Chamber (Jenny Wakeman v. 6 Tailed Kokuō)

Castle Rooftop (Pikachu v. 'False' Bowser)

Sight of Cosmo's Death (Sonic Heroes v. Madara Uchiha)

Forest Temple (Cosmo the Seedrian v. Phantom Ganon)

Battlefield of Lava (Heroes v. Kaguya Ōtsutsuki/Mane 6 & Austin Keith v. Twivine Sparkle/Spike v. Mane-iac Sparkle)

Skies Above Domino (Team Sonic v. Egg Dragon Tree)

The ARK (Tyler Keith v. Winged Dragon of Ra)

Valley of Seers (Link v. Agaran)

Palace of Shadow (Mario Bros. v. Shadow Queen)

Spike's Mind (Twilight Sparkle v. 'Dark' Spike)

Samurai Bridge (Naruto v. Cia)

Corrupted Tree of Harmony Stage (Austin Keith v. Twivine Sparkle)

Ancient Castle (Yugi Muto, Jaden Yuki, & Yusei Fudo v. Nightmare Moon & Wizzro)

Egg Galaxy Reactor (Heroes v. Giga Bowser)

Cluster Mothership (Heroes v. Delta Vexus)

Death Egg Core (Heroes v. Sage of the Six Paths Madara Uchiha)

The Doomsday Zone (Heroes v. Villains/Heroes v. Egg Ten-Tails)

Core of the Moon (Ultimate Sonic v. Ten-Tails Eggman)

Final Destination (Heroes v. Hyper Fleetfoot; Hyper Shadic v. Alpha Fleetfoot; Final Boss: Omega Sonic v. Ultimate God Fleetfoot)