While I can't play Portal 2 right now, I found this, which demonstrates that most portal 2 co-op chambers need only one person to solve the puzzle, using some glitches. In that video, there's several interesting glitches, including reportal glitch, TRT, and this awesome glitch. When I first played Portal 2, I was disappointed because many glitches in Portal disappeared, and thought that there's no glitch in Portal 2 (and that was totally wrong, as you can see above).
Are there any other glitches in Portal 2? For example, when I was playing Portal 2 co-op, I found that there are some glitch about gel, so I could step on blue gel which was blocked by a wall.