Digimon Tamers - Season 1 Episode 36 The Battle Within

Gallantmon faces Beelzemon in a tough one-on-one battle. During the battle, Gallantmon destroys Behemoth and rescues Kazu and Kenta which causes them to realize that Takato has merged with Guilmon. Meanwhile, the Sovereign sends his last Deva Chatsuramon to destroy Lopmon for being a traitor. Chatsuramon goes to kill Suzie and Lopmon, but Terriermon takes the hit, saving them and mortally injuring him. Before Chatsuramon can do more, Gallantmon destroys him, taking out the last Deva, but Beelzemon absorbs his data which makes him stronger. Beelzemon beats down Gallantmon and is about to kill him, but Guardromon and Kazu intervene and buy Gallantmon enough time to recover. Beelzemon's attacks do no damage to him after that and he runs out of ammo. Once that's done, Gallantmon blasts Beelzemon with his Shield of the Just, finally defeating him. Gallantmon goes to kill him, but Jeri stops him as it won't bring Leomon back, and orders Takato to spare Beelzemon’s life. Beelzemon remembers his own Tamers and leaves, regretting his actions while Takato gains a new D3 Digivice.