The three players are set to make their United debut on Sunday in the Premier League opener against Arsenal at Old Trafford.
Mbeumo said that Cunha is a skilled player and that training together has helped them develop a strong partnership.
"We've been doing some striker work and forward work. I think we still have some freedom up front, but there are some principles to respect," Mbeumo explained.
He added that he's willing to play in any position and that the manager will decide how to use the players.
Mbeumo also spoke highly of Sesko, saying that he's a "cool guy" who is easy to get along with.
"I think it's important to help people settle in, especially when they come from another league and don't know much about things here," Mbeumo said.
"I think it's essential to make them feel at home already. I think everyone is doing this naturally, we don't really calculate anything, but I think this is really important."