Here is the announcement
Andre Tricoteux was the one to reveal that he was involved in the making of Deadpool, although he didn't reveal his role. It could have been expected for him to do stunt work, just like in Seventh Son.
That’s a wrap for me! Thanks to all the cast and crew. @VancityReynolds @briannahilde @edskrein @ginacarano #Deadpool #Colossus #yvrshoots
"” Andre Tricoteux (@andretricoteux) May 29, 2015
However, his tweet was quickly followed by an answer from Gina Carano, who also named him as the best Colossus. You’re the best #Colossus a person could ask for Andre. https://t.co/mObR1L6TDR
"” Gina Carano (@ginacarano) May 29, 2015
It is unknown at this moment how much of the actor will be seen as Colossus. Given the fact that he was wearing a motion-capture suit on the set, it can be believed that, ultimately, the voice of Colossus will be provided by another actor, much like it was with Rocket Raccoon (played by Sean Gunn and voiced by Bradley Cooper) in Guardians of the Galaxy.
