Legitimate permutations include the entire plan plus all or part of the counterplan and nothing else. Topical counterplans are almost always legitimate. Conditionality is not indefensible. International fiat is hard to win, but I've seen it happen. I'm often not certain what exactly the permutation is.
Debaters talk fast.
There is almost an hour from the end of 2AC until the end of the round. I have a bad memory. These factors make it difficult to determine the permutation's legitimacy or desirability. Non-topical exclusions are all the more legitimate. Whether or not the counterplan competes, or actually excludes something from the plan is a different question that you must resolve.