Neo Metal Sonic is just Metal Sonic powered up by a chaos emerald, and Chaos had the power to eat the chaos emerald to empower himself, so
if Metal scan the biodata of Chaos he would get the ability to empower himself with our chaos emerald and become Neo Metal Sonic.
For more detail, Chaos was capable of transforming like that due to the master emerald empowering him, causing him to mutate, but the ability
to absorb chaos energy is not exclusive to him, is just a trait from the Chao that got amplified, in the games the Chao can absorb traits from
animals (the chaos gardens) and energy from the chaos drives to transform, or as Chaos demonstrated the master emerald.