In addition to 9 new Enviro 400H City buses from the Plymouth Citybus report (please see
https://beta.companieshouse.gov.uk/company/02004966/filing-history), there are also other second hand Enviro 400s coming to Plymouth (not 460-476 and not from London) in addition to the recently acquired ones from the London operations of the Go Ahead Group.
There is no information on which routes they will be placed on or which Enviro 400s will be heading to Plymouth. However, it is believed that they will replace older double deckers that Plymouth Citybus operate.
Above: A second hand Enviro 400 already in operation in Plymouth Citybus and not one due to be acquired.