I think its a good feature if you can select what lead pokemon you want to use and see other' lead mon on the matchmaking with random people before attempting the raid battle. Right now the lead mon are determined by the pokemon in your first party without knowing other people lead mon. This may result in bad early game like you begin with 4 tailwind or 4 screen setter. By knowing other lead mon and able to choose what lead mon to begin with, this may help a little on the early phase of the raid. I might have a wrong idea so if you have other poin of view, let me know!

 

PS: I understand that raid battle are mostly the best when you do it with your friends as you can communicate and build a strategy better than with random people.

Signup is currently in its very early stages, we'd like to expand upon it with changes like this as we develop the feature more.