Metal Sonic is one of the big fighters in this league and is not to be underestimated. Rayquaza may be a cool dragon but he can’t take on the power. Metal Sonic has the ability to transform into Metal Overlord, which is his strongest form. In this form, he was able to take on multiple opponents who were moving at a tremendous speed and his durability is off the charts. Rayquaza wouldn’t be able to match his speed or sheer ferocity and while he has a lot of battle experience, Metal Sonic’s AI is too advanced and he would be able to make plans to defeat him. Metal Sonic wins.
A link to the original image is below and This illustration was created by ToaAntan.