S2·E4 Come Forth, Sword of Berserk!

Geo explains the quest for the OOParts to Sonia, who expresses interest in helping. Rogue attacks again, and the duo transform into Mega Man and Lyra Note to fight. Rogue attempts to take the Sword of Zerker, but Mega Man suddenly uses it to transform into the Thunder Zerker form, and defeats him.