This is only doable by 2 players at a time edit it yourself to make 3 or more its easy enough or it should be.
Code:
command /swap <player> <player>:
trigger:
set {target player} to arg 1
set {target player-2} to arg 2
wait 300 seconds
broadcast " <dark red>Teleporting in 5"
wait 1 second
broadcast "<dark red>4"
wait 1 second
broadcast "<dark red>3"
wait 1 second
broadcast "<dark red>2"
wait 1 second
broadcast "<dark red>1"
broadcast "<dark red>Teleporting"
wait 1 second
set {loc} to the location at arg 1
set {loc1} to the location at arg 2
Teleport arg 1 to {loc1}
Teleport arg 2 to {loc}
Thats all have fun!!!