Dr. Eggman

Dr. Ivo "Eggman" Robotnik is an evil scientist bent on taking over the world to establish his Eggman Empire only to be stopped by his archnemesis, Sonic the Hedgehog. Since then he's always made it his top priority to defeat Sonic and his friends once and for all no matter the cost. In his role of FiE, he plays the part as a villain as he did with Sonic, caused havoc in Equestria, and even joining forces with the villains of the Mane Six.

Upon Discovering Equestria
Eggman was once again defeated by Sonic and his friends, and he's starting to run out of ideas though he's not going to give up. Later, a robot of his discovered a hurricane that was very out of place, in fact in the eye was a portal. He sent his drones to scout the area and find that this portal lead to a world that is inhabited by ponies, unicorns, and pegasi, the world of Equestria.

Action Taken
Eggman sent in his newest robot squad, the Hex Squad, a team of 6 colored bots. Upon their arrival in Equestria they soon found themselves fighting the Mane 6 and were defeated. After this Eggman left in his Egg Carrier and entered the portal, causing a shift to occur that dragged Sonic and his friends, as well as the emeralds, into the new world. Later Eggman created a bot called the E-1337 or E-leet, that he used to try to gain a foothold against the heroes. However this backfired as the bot was beaten by the heroes.

Egg Emperor Mk. II​
Eggman created a team of seven robots, that gained all the chaos emeralds and retreated with him to a fake base in the Appleloosan plains. There the bots after being beaten merged with Eggman's newest Egg Emperor model to created a near invincible Egg Emperor MK. II. after discovering its weakpoint, our heroes defeated him and regained the emeralds just in time to fight Stargazer.

Mystery Creation
While Chrysalis was teamed up with Eggman she stumbled upon a massive construction project, when asked about what it was Eggman replied, "My last resort"

No one knows what exactly it is, but it's obviously something that requires immense power as determined by dialogue between Eggman and the Construction Bots.