Neo Metal Sonic is an upgraded version of Sonic's doppelganger.  While only revealed at the end, he takes on a much bigger role later in the comic. Being a Robot Mastermind, the voice should be cold, but not emotionless. He is very meticulous and obsessed with power, which shows through his voice, despite being a robot. We do not have a preference on using an impression or not, but if you choose to do so, we would recommend to take inspiration from Ryan Drummond in Sonic Heroes. 

If you plan on using a filter, please provide the lines both with and without it.