[EricH]

Originally Posted by nicholsjj

The image you displayed shows a one on one defense in which R1 could go under the pyramid to get free so no this is not an alliance blockading the field.

Actually, it is. IF R1 cannot go under the pyramid, it is blockading. Or, if a third blue robot B3 was in front of the pyramid, it's blockading.

Additionally, the rule specifically calls out "to stop the flow of the match". If I were a ref, and I saw that setup (assuming B1 and B2 are not on their respective ways elsewhere), I would probably call the penalty regardless of whether R1, R2, and R3 could go under the pyramid, as B1 and B2 are attempting to blockade the field to stop the flow of the match--and the rule does not require a specific opposing robot action attempt to trigger enforcement.