There are one or two Mk1 EMUs used as "tractor units" in 3rd rail land, but aside from that any shunting required would most likely be an 08.
FCC does own the last remaining class 03 on the mainline, based at Hornsey in London, which may or may not qualify as "southern".
The class 09s are historically linked with the southern, but can be found elsewhere these days as they seem to be used interchangeably with 08s.