JET ENGINE
A jet engine built into Metal's Sonic torso, capable of breaking the sound barrier and in possession of full flight capabilities even to the extent of interplanetary travel. Stripped of almost all of its functionality, it now serves as a minor boost to Metal's ability to get around in the form of a double jump. The jet can only ignite for a split second, but exerts enough force to propel him a few feet higher than he can jump. It is also subjected to a cooldown between each use.
CHAOS EMERALD (RED)
A gem of unimaginable power native to Metal's world referred to as a "chaos emerald", red in coloration despite its name. Part of a set of seven, the chaos emeralds are said to possess the power to grant wishes and create miracles, should their possessor have the knowhow to properly utilize them. In Jigoku, the chaos emerald no longer provides Metal with chaos energy but rather allows him to tap into "soul energy", the native energy source of Hell. Functionally, it provides him with an unending source of energy to operate with.
DOPPLEGANGER
One of Metal's abilities unique to his "neo" form. He can become a silvery, liquid metal substance akin to mercury which he can freely shapeshift with. He has used this ability in the past to imitate both Sonic and Eggman with extreme accuracy, down to their voices and personality. On top of this his transformation ability is incredibly accurate, as although he remains made of metal, the texture and feel of things like skin or hair perfectly imitate the original. However, it appears to possess a limit in terms of the size it can expand to - although he was capable of becoming Eggman, who stands twice the height of Metal's base form, in order to become the enormous Metal Overlord, he was forced to create a body from the debris of a warship and instead transformed his body into its "head", which allowed him to control the body from there by connecting to it.
???
A fragment of his original power, allowing him to display just a sample of his real speed.
???
A cluster of data from the echidna species. If unlocked, it could open up new potential.