The info at Comicvine stated that Gentle has the potential to become the strongest in Marvel Universe, but for short period (seizure and strain on his body).
vs.
Who wins in your opinion?
KIN
KingD19Shai-Gen's Enigmatic Wong
Colossus in a landslide. Gentle only did two things before really being phased out. He punched a ONE Sentinel and knocked it over, and fought demons in Limbo. Nothing Colossus can't replicate with ease.