Super Mario Bros. Z

History
Super Mario Bros. Z is a flash animation series created by Mark Haynes, who also goes by the username Alvin-Earthworm. The flash series originally debuted in 2006, but was subsequently canceled after the eighth episode of the series. In late 2015, Mark announced his interest in rebooting the series from the ground up, remaking older episodes and expressing interests in completing the series as a whole.

Plot
Metallix, a vicious robotic version of Sonic the Hedgehog created by Dr. Eggman, is the result of Metal Sonic fusing with various other Sonic robots created by Eggman. As Metal Sonic transformed into Metallix, Dr. Eggman condemned Metallix's actions - resulting in Metallix rebelling against Eggman and subsequently destroying the Death Egg in the process. As the Death Egg crashed into Mobius, Metallix sought to find the seven Chaos Emeralds, as well as eliminating anyone who stood in its way.

Metallix methodically killed all of the inhabitants of the planet Mobius, including Sonic's closest friends. As Metallix was about to obtain the final Chaos Emerald, Sonic battle furiously to try and prevent Metallix from achieving its goal. As things looked dim for Sonic, Shadow appeared and warped the Chaos Emeralds to the Mushroom Kingdom; Mario's world. Utilizing the energy harnessed from the Chaos Emeralds, Metallix used Chaos Control in order to track the Chaos Emeralds down by also warping to the Mushroom Kingdom. In an effort to try and stop Metallix, Sonic and Shadow found the wreckage of the Death Egg and assembled a capsule to harness enough power to pursue Metallix.

As Sonic and Shadow arrive in the Mushroom Kingdom, they quickly enlist the aid of Mario, Luigi. Sonic informs Mario of their search for the Chaos Emeralds, along with how crucial it is to make sure they obtain the emeralds before more sinister forces do. Mario and Luigi agree to help in Sonic's quest and also seek out the help of their friend Yoshi.