Varela, 23, joined Eintracht Frankfurt on loan from Manchester United in the summer.
Subotic, 28, joined Cologne on a six-month loan from in January after enduring a difficult 2016.
Javier 'Chicharito' Hernandez discusses his transfer prospects, his time at Real Madrid and talks about life at Leverkusen.
Lothar Matthaus has said "there is no place" for Thomas Muller in Carlo Ancelotti's strongest Bayern Munich XI.
Johansson said: "I'm very pleased to join FC Bayern from this summer, and I am looking forward to the challenge."
The rule stipulates that more than 50 percent of a club must be owned by its members, but there are exceptions for company-owned clubs.