That’s up to your team!
I imagine that if the first person starts out in iambic pentameter, it’d be a good idea to stick with it, or vary in a predictable way (e.g. stanza 2 is iambic tetrameter, stanza 3 is trimeter, repeat, or just alternate between two of those).
If the first person starts out in free verse with all lines around the same length, maybe stick with that. Similarly if it’s a case of wildly varying line lengths. Or you could write the stanza that sticks out.
It truly is a case of “anything goes”, but please seek feedback from your collaborators if you’re going to do something drastic!
Also, if that’s your one remaining question, I am delighted to have not done such a dodgy botch job of my instructions this time