Mephiles is first seen after Dr. Eggman mobilises the Death Egg, where he is seen observing the Death Egg emerge from the water. Mephiles takes notice of the Dark Heroes of Legend and their comrades who felt the earthquake caused by the Death Egg, prompting Mephiles to challenge Sonic the Hedgehog, Goku, and Link so he can test their abilities. Before the battle, Mephiles states that he has been lost in limbo, but the Time Eater has given him the chance to live again. Mephiles later watches as the heroes battle against the villains, but captures the energy produced by the battle and gives it to Tikal, though his reasons for doing so are unknown. Mephiles then attempts to fight Wiseman, but is defeated quickly despite summoning Iblis to the fight and flees into the sewers. Mephiles is then taken by Dr. Eggman, and joins the villains from that point onward. After Fight to the Finish 2 Arc, the Heroes Of Legend had fell from their grace due to Mehpiles, he later hid in Smash City in attempting to escape from them being in disguised, however since Tikal resided here, she saw the disguised Mephiles and was confronted him, revealing his identity to her, she challenges him to an fight, where if she wins he will reveal what he has done and if he wins he will escape. Tikal wins the battle and interrogates him about what he has done, Mehpiles explains his actions to her and she gives the unveils the secret to the Heroes Of Legend so that they earn back their grace. Season 25, Mephiles reappears after Modern Sonic saves Classic Sonic from Mechtavius Destroyer, where he reveals that Metal Sonic harnessed the power of the Smash Core to create a new world, but he decided to completely destroy the barriers of time and space so his world couldn't be undone, like the previous alternate timelines were. Mephiles then explains that this brought back all the villains that didn't exist anymore, but Metal Sonic became stronger as a result and conquered the Smash World, though Mephiles also reveals that Metal Sonic is so confident in his victory that he just lets the people do what they want. After Modern Sonic says that Metal Sonic isn't benevolent and that he is insane, Mephiles counters by saying that Sonic was the one who drove Metal Sonic insane, and even questions if Sonic ever considered that Metal Sonic had emotions of his own and wasn't just a robot. Mephiles then looks at Classic Sonic and states that he is lucky that he didn't do any of these atrocities, causing Modern Sonic to grab Mephiles and yells at him for accusing his younger self of being responsible for this. However, Mephiles retorts that he isn't accussing, but rather he is saying that Sonic is responsible for Metal Sonic's insanity and Classic Sonic is lucky that he hasn't driven Metal Sonic insane yet. Mephiles then leaves, but not before leaving a frightening thought on Sonic's head by stating that the Heroes of Legend may be the true cause for the possible apocalypse, stating the recent events that have occurred have been caused by the Heroes of Legend. After this, Mephiles goes to Will Harangue and gives him several tapes as part of Operation: Smear. After the smear campaign is a success, Mephiles appears before the Heroes of Legend, Ben Tennyson, and Shadow, revealing his part in the smear campaign, and flees when they are distracted by the arrival of the villains. Mephiles then battles against Metal Sonic, the Heroes of Legend, Ben Tennyson, and Shadow the Hedgehog, and is defeated, but mocks the Heroes of Legend about their fall from grace, since everyone is now convinced they will kill them all since the battle was on TV. However, the League of Villains, who showed up during the fight, exile Mephiles from their ranks due to how low he stooped to make the Heroes of Legend suffer, and is even blasted by Mechtavius Destroyer. Later, Ben, Shadow, and the Heroes of Legend's Bakugan go back in time to before Mephiles went to fight Metal Sonic, and tell everyone to focus on Mephiles. Desperate, Mephiles combines with Iblis to form Solaris, but is defeated after a long battle by the Heroes of Legend after they are consumed by their darkness. Afterwards, Mephiles and Iblis are banished to the creepypasta realm to extend their suffering, and Mephiles even begs Shadow to save him, but is unsuccessful since Shadow doesn't like him anyway and that E-123 Omega and E-102 Gamma were held at gunpoint. In the second arc of Season 25, it is revealed that the dark Smash Core was sent to the creepypasta realm, and caused Mephiles to mutate into an amored version of himself that he calls Nightmare, while Iblis was mutated into a Darkus Spatterix and Darkus Stronk. Mephiles is later betrayed by Mechtavius Destroyer, who was linked to him, after the psychopath breaks free, and is vaporized by Mechtavius Destroyer. However, Nazo later reveals to Mario and Princess Peach that the Smash Core is actually Mephiles' heart, which was ripped out of him when Mephiles tried to avoid being erased from existence, making Mephiles responsible for everything that has happened up until now. Mephiles is later revived, but is ultimately betrayed by Mechtavius Destroyer and is killed and absorbed by the tyrant along with Samus Aran. Mephiles is later revived when Zane Truesdale uses De-Fusion to release Mechtavius Destroyer's victims. Mephiles is later seen aboard the Comet Observatory when Vilgax explains to the Heroes of Legend and Rosalina that Coredegon merely gave physical bodies to the creepypastas and states that Silver the Hedgehog could become like Dark Silver. Mephiles, having seen Dark Silver in action, decides to see if Vilgax is correct. It is also shown that Mephiles has acquired 60 of the Bronze Power Stars that contains Diagon's essence, which he uses to attract the other 60 Bronze Stars to him to initiate the Grand Design. Mephiles is later killed in Season 30 by Mechtavius Destroyer while buying time for the heroes and villains to escape. Mephiles is revived in Season 31, and assists the heroes and villains in the final battle against Mechtavius Destroyer. After Mechtavius Destroyer is defeated, Mephiles returns to the main dimension and becomes the leader of Team Nightmare, consisting of himself, Fleetway Super Sonic, and Dark Silver. In Season 32, Mephiles continues to antagonize the heroes until Mechtavius Destroyer is vaporized by the Heroes of Legend. Upon Mechtavius Destroyer's death, Mephiles laughs evilly, stating that while the Destroyer of Worlds is finally gone, the battle is far from over. Since he was linked to Mechtavius Destroyer, Mephiles is erased from existence due to his death. Mephiles is later revived by the Heroes of Legend as part of their final plan to remake the world in their image. In Season 34, it is revealed that while Mephiles' heart became Mechtavius Destroyer, his soul was thrusted to the beginning of the Smash World, where he merged with Master Hand and became his mind, making Mephiles the true mastermind behind everything that has happened. Despite having the power of the Creator, Mephiles is ultimately defeated by The Creator's Triune, but vows to get vengenance one day. During the second Neo Smash Champion Tourney, Mephiles hides in the shadows, with Team Chaos being his primary enforcers. During the finale of Season 34, Mephiles prepares to destroy the heroes and villains once and for all, but is severed from Master Hand by Mecha Sally, resulting in Mephiles fading from existence. Later, during The Dimensional War, following the revelation that Midna is the leader of the Revolutionaries, Mephiles is ressurected by Sasuke Uchiha in order to figure out who the Heroes of Legend's enemies really are. Uninterested in Midna's war, and aware that the Heroes of Legend have surpassed him completely, Mephiles muses about how low the Heroes of Legend have fallen if they resorted to reviving him, infuriating Sonic. Despite this, Mephiles informs the Heroes of Legend that he can't choose who the Heroes of Legend's enemies are, stating that they have to figure that out themselves if they wish to remake the world. Mephiles later helps Zero, N, and Terra Branford escape from the Revolutionaries, and tells the Revolutionaries to not be so hasty to go after them, shocking the Revolutionaries with the fact that he is alive and well. When Vile asks what the big deal is, Mephiles sarcastically apologizes, stating that Ganondorf, King Dedede, Zelda, Wolf O'Donnell, Dark Samus, Sigma, and Mechtavius Destroyer are the only ones who know him, before noticing Obito Uchiha, sarcastically saying he didn't recognize him without his mask, and introduces himself to Ghirahim, Vile, and Madara Uchiha. Mephiles then states that he has no intention to fight the Revolutionaries, merely asking them to take him to Midna, which King Dedede reluctantly does. Upon arriving at the Brawl Spectator Society HQ, Mephiles reveals himself to Midna, much to her shock and horror, and realizes that she is the child who impaled him while he possessed Master Hand when he threatened to punish her with death if she tried to rebel against him. Mephiles tells Midna not to worry, as he is no longer the Creator and therefore her rebellion isn't his problem. However, Mephiles tells Midna that he is impressed with her rebellion, stating he never knew of the Revolutionaries during his entire life or that Zelda, Wolf, and King Dedede were a part of the organization, but warns her that defying the Creator has its consequences, and the Heroes of Legend could revive what she doesn't want in the new world. When Midna falls on her knees in fear, Mephiles taunts Midna for still fearing him even when he has lost his power, stating that her rebellion is doomed to failure and that he will seize control of the Revolutionaries when that happens, and eventually rise back to power. Mephiles later learns of Starly, one of Stario's bodyguards, and reveals to Coredegon that Starly is his reincarnation while initiating his plan to become whole again, which ultimately succeeds when Starly accepts her heritage as a part of Solaris. Despite Starly remaining the dominant mind, Mephiles continues to exist within Starly's subconscious along with Mechtavius Destroyer.
Mephiles the Dark is mainly seen in his third form from Sonic '06.
|Sonic the Hedgehog, Goku, and Link||No outcome|
|Naruto Uzumaki, Sasuke Uchiha, Dan Kuso, Gunz Lazar, and Spectra Phantom||No outcome (Tag with Dr. Eggman, Ganondorf, Frieza, Cell, and Android 18)|
|Metal Sonic, Heroes of Legend, Ben Tennyson, and Shadow the Hedgehog||Lose|
|Heroes of Legend, Heroes of the World, and the League of Villains||Lose|
|Naruto Uzumaki||No outcome|
|Mechtavius Destroyer||Lose (Tag with Samus Aran)|
|Mechtavius Destroyer||Lose (Tag with Nazo, Dark Silver, Metal Mario, Dry Bowser, Frightful Four, Fawful, and Evil Way Big)|
|The Creator's Triune||Lose|
- Despite the fact that the events of Sonic '06 were erased, Mephiles is alive due to the Smash Bros. Galaxy being within the White Space, which has no time. However, Mephiles does know that he was erased from existence. This is later revealed to be due to the fact that Sonic.exe cheated Mephiles's fate for his plans.
- Mephiles appears to be able to see far distances, as he picked Sonic, Goku, and Link as his first opponents, which is strange because their respective enemies (Dr. Eggman for Sonic, Android 18 for Goku, and Ganondorf for Link) were onboard the Death Egg so they could find Mephiles. This means Mephiles must have seen them from afar.
- Mephiles is very arrogant, as despite the presence of Coredegon, Slycerak, Exostriker, and Mandibor on the Death Egg, Mephiles did not choose to battle any of the Battle Brawlers. Ironically, Mephiles has not won a battle in the series as it is either interrupted, Mephiles fleeing, or when Tikal was to strong to defeat him due to her having bakugan powers.
- Of all the villains in the series, Mephiles is the second cruelest after Coredegon/Mechtavius Destroyer, as his smear campaign caused Sonic to break down in tears, something the other villains, even Mechtavius Destroyer, think is low even for him.
- Ironically, Mephiles is a coward as well, since he attacks when his opponent isn't looking, he fled during his first fight, used the Heroes of Legend to distract the villains rather than fight them himself, and even begged hysterically for Shadow to save him from the creepypasta realm.
- Mephiles hates Shadow due to being sealed in the Scepter of Darkness by him.