I'm trying to make a sort of puzzle/adventure for a group of 6 friends, and I want it to start once everyone is standing on a separate pressure plate. Once they are, they would all be teleported to a location. I can't figure out a way to do this, with command blocks or otherwise. This would be a part of a pre-existing world, and I want all of the pressure plates to need to be powered before the command is executed.
You could have a single block (always active repeater) that runs the teleport command if block ~ ~ ~ (the coords of the pressure plate) minecraft:stone_pressure_plate[powered=true] etc. to make it run only if all of them are powered at the same time. Im assuming that they all will be teleported to the same place. If not, then use it to change a score to 1 which then allows each individual teleport to run. Let me know if you have any more questions and ill be happy to help