Try the following to see the help. Remember if you didn't install the mcollective puppet agent, not just the mcollective agent, on the servers and the mcollective puppet client on your local machine mco won't be able to run (or see) the puppet plugin. Or the service pluging. Or the nrpe plugin. Or the package plugin.
mco help puppet
and list of mcollective plugsin I have installed
~ $ dpkg --list | grep mcollective
ii mcollective 2.5.2-1puppetlabs1
ii mcollective-common 2.5.2-1puppetlabs1
ii mcollective-filemgr-agent 1.0.1-1
ii mcollective-filemgr-common 1.0.1-1
ii mcollective-iptables-agent 3.0.1-1
ii mcollective-iptables-common 3.0.1-1
ii mcollective-nrpe-agent 3.0.2-1
ii mcollective-nrpe-common 3.0.2-1
ii mcollective-package-agent 4.3.0-1puppetlabs1
ii mcollective-package-common 4.3.0-1puppetlabs1
ii mcollective-puppet-agent 1.7.2-1puppetlabs1
ii mcollective-puppet-common 1.7.2-1puppetlabs1
ii mcollective-service-agent 3.1.2-1
ii mcollective-service-common 3.1.2-1
When you install a plugin you will need the -client package on the machine from which you run your mco command line statements. The agent packages need to be on all the other machines.
I prefer to stop the service completely for an upgrade. mco puppet disable will leave the daemon running which makes the upgrade more likely to fail. Here are the command I use. Stop, upgrade using batch sizes so all the the agent aren't started at once, and then check status.
mco service puppet stop -S "environment=stage" # or whatever filter
mco package puppet upgrade --batch 2 --batch-sleep 30 -S "environment=stage"
mco puppet status -S "environment=stage"