Quote Originally Posted by bitpicker View Post
Really any verb (within reason, i.e. verbs signifying an activity several people may perform together)?
Err... Well, you are right, I confused it with that imperative cooperative (=future plural first person), which is indeed works virtually for any verb.

For most (perfective) verbs this form (= past plural) means just brutal imperative (impolite order). Though I can imagine that it is used as imperative cooperative in some contexts... Oh, my. The more I think about it, the more complicated it looks.

Пошёл работать = пойду работать = I should return to work now.
No, this is not imperative-like. It is different situation.

Перешли мне, пожалуйста, его ещё раз. = Please send it to me once more.
Again wrong example. This is a regular imperative, not past plural (otherwise it should be "переслали").

Начали = Let's begin!
This is OK. And any perfective verb with meaning "to start to" can work here... Depending on context.