After encountering Shadow who then transforms into his super form, Sonic and Amy also transform into their super forms and then after some brief opening lines Sonic and Shadow begin fighting. During the fighting, it is revealed how Amy got her super form which happened to her while Shadow trained her. Afterwards, she then decides to fight both Sonic and Shadow to test her training. (Before she does however, the DS near Mario shows that her power level is >9000!!!) After attacking Shadow and Sonic (she slams the latter into a hill which she wonders "did I overdo it?") Shadow attacks her and lectures her on being weak and prepares to attack her but when he tries to blast her with a dark super beam Sonic stops the attack and deflects it away. Shortly afterwards, Mario and friends wake up to see that Rouge has stolen the DS radar! So Knuckles tries to stop her but ultimately fails when he gets knocked down. Enraged, Sonic charges her but Shadow warps Rouge out of harm's way and goads Sonic to finish the fight. After a short, quick fighting sequence they power up again and try to slam into each other which somehow triggers an unusual memory of them being best friends. It is then revealed that Namine is messing with their memories with Roxas looking on. Then, the resulting explosion from the chaos energy knocks both Sonic and Shadow back and out of their super forms. Afterwards, Knuckles and Tails chase after Rouge to try to get the radar back. But they have little they can do against Rouge's quick and heavy attacks (Knuckles even fails hilariously at a Shoryuken and gets knocked back down in the ground!) Then the DS radar shows that Rouge levels up to level 10, however it also shows that the Mario Bros. power level has increased! Then they fire the "Brother Blaze" which is a powerful combo of BOTH of their fireballs. But before the attack hits, Yoshi comes out of nowhere and quickly pummels Rouge with the "Yoshi Barrage" to add more damage to this surprise attack that subsequently defeats Rouge which gives the fighters the new techniques as well as level up Mario and Luigi to level 14 and Yoshi to level 12! But Shadow rises up again after what happened earlier and the team prepares to attack him but Sonic stops them before they can seeing that something isn't right. And to further the point, the 2 chaos emeralds dropped nearby suddenly revives Amy in a blaze of negative chaos energy transforming her into Heartless Amy! As a result, the emeralds have then become temporarily drained of their energy. Then, she/it proceeds to attack the rest of the team without mercy. After saving the others, Sonic brings up the emerald radar which shows that apparently Heartless Amy has NO weakness! Then while the fighting continues against Heartless Amy, Namine and Roxas look on in horror as they can't rearrange Amy's memories most likely due to the negative chaos energy in Amy. However, even after attacking Shadow in cold blood Amy still tries to regain control of her body after hearing Sonic's voice. Sonic then resorts to using his last resort; his werehog form after creating an artificial moon much like how Vegeta does from the Dragonball Z series and then attacks Amy in a desperate attempt to stop her. But after knocking her down, the darkness draws closer to Amy's heart and she then attacks Sonic again while also breaking the moon he created. As she prepares to fire a blast of pure dark energy at Sonic he finally reveals his love for her which reverts her back to normal. Fortunately, a mysterious warrior appears in the nick of time to deflect the blast presumably at Amy and then the episode ends with Roxas and Namine preparing to welcome Misty into the world.