Conversation so far:
What special powers did Kevin Sydney have?
Kevin Sydney is a mutant metamorph with the ability to alter his physical appearance and voice at will to resemble that of any person he chooses.
Did Kevin Sydney fight anyone using metamorph?
Kevin Sydney was a short-lived adversary for the X-Men.

Question: What else can you tell me of interest?
Self-contained rewrite: What else can you tell me about Kevin Sydney and his powers?