MegaBug

The Megabug, also referred to as the MegaDragon, is the main antagonist of the 2017 Nintendo Video Game, Mario + Rabbids: Kingdom Battle. It is an enigmatic yet extremely evil creature that wants to destroy the world.

MegaBug
As the MegaBug, it has an almost indescribable appearance. It is a Phoenix-Dragon like creature with some very notable features: it has very bright yellow eyes, a swirly tail, two large wings that is bigger than its body itself, yellow, red, and neon colored colors around it's body shining, and a very strange face.

MegaDragonBowser
When Bowser comes home from vacation early, the MegaBug starts attacking him making him unconscious. It then possesses his body to make it's normal weak self a very strong creature, which results into the atrocious being that is Megadragonbowser.

Like the normal Bowser would, it keeps the red mane, the iconic spikey green shell, the yellow dragon skin, and the handcuffs, but it also gives Bowser more terrifying features. Bowser's body gets a yellow-red aura around it similarly to the MegaBug. It gains extremely bright yellow eyes, but its most notable feature is the new Phoenix-Dragon wings it gives the body.

Biography
While little is known about the MegaBug, we do know that throughout the game, it is the very reason why everything bad happened, and that whenever the heroes tries do something, it grows bigger and bigger, and comes closer to it's main goal, to destroy and consume everything in the world. When it possesses Bowser, Bowser Jr. Does show honorability and begs the heroes to save his dad.

During its boss battle, it uses minions for a big part of the battle, but will occasionally itself attack too. At times it will even attack its minions. However, whenever it spins with the shell it becomes vulnerable.

After getting defeated, it tries to kill the heroes once and for all in a last ditch effort, but fails in doing so, falls into lava, and finally dies.

Powers/Abilities
While not very powerful itself, as seen when it doesn't even get a fighting chance at the heroes after getting defeated and instantly gets shot down, when it fuses with Bowser it gains a lot of power. It obtains every power that Bowser already had, like Shell-Spinning, fire-breathing, brute strength, etc, but also keeps its own ability to fly, making it a very dangerous foe.

Trivia

 * The MegaBug is no doubt the most evil Mario Villain along with King Boo and Dimentio. Interestingly enough, The MegaBug shares similarities with these two: both the MegaBug and King Boo can possess people's bodies, and both of them did that on Bowser to make themselves more powerful. Both the MegaBug and Dimentio attempt cataclysm as their main goal.
 * The MegaBug shares a very notable resemblance to the legendary Pokémon Zygarde.
 * Its design also shares similarities to Solaris second form. And it also does share some similarities with Mephiles the Dark from the same game, as both of them are demonic beings, who, while technically made out of evil, still can choose what their actions will be, and choose to do horrendous things.