Poccers are usually high armor/high HP (or both) units that can withstand lots of damage in order to poc and take up a lot of space for sitting and Poc blocking?.
Usually, clouters? are good for the job. Good poccer units include the Behemoth, Quorg, Abomination, Wraith, Mephit, Imp. Clouters are excellent for this job because their higher chassis allows them to take huge amounts of sustained damage as well as move faster than the average unit to the poc.