So Everyone pick's the Clippers, so we don't know who they play, it also means we can eliminate them from the rest of our logic moving forward.
Bobby Picks Bulls, Warriors, Cavs, and Donnie Picks Spurs, Thunder, Warriors. This tells us the Warriors played some yet unnamed team. Also the Bulls/Cavs, played Spurs/Thunder.
Since Reggie Picks Hawks, Bulls, Thunder We now have the missing team that played the Warriors, and know the Bulls did NOT play the Thunder. So Bulls had to play the Spurs, and Cavs had to play the Thunder.
So Clippers played and Unknown Team, that could be assumed was the Knicks, but the riddle didn't specify that the Knicks were playing, only that no one picked them. No one would have picked any other team that was not playing either.
Bulls played the Spurs
Warriors played the Hawks
Cavs Played the Thunder.