Toward the end of last year Tutu was on the field quite a bit and seemed to do fine. Tutu is the only WR we have that can really stretch the field. Kupp can go deep but he does it by somehow getting wide open when the defense is totally focused on where he. Jefferson also has shown he can get open but as the #2 guy the defense will be paying more attention to him.
Tutu showed he could play last year and that he has a really good set of hands. He also showed he can get open deep and either catch the ball or draw a penalty. Tutu and Skow are both relatively known commodities and bring something totally different to the table. I expect that depending on the situation the will switch of on being the #3 WR and will both be on the field in a 4 WR set. Both Tutu and Skow should get plenty of playing time and opportunities. If every body stays healthy I don't see anyone else getting regular snaps.
While Pacu seems interesting and provides plenty of reason for optimism he is a 5th rounder with a history of injuries. While I would certainly give him an edge on making the team those last 2 WR slots positions are wide open and the ability to play special teams will come into play when deciding the final cuts.