Pretty easy for me.
target the commander or Lieutenant with all, throw the spear to him.
When they are close, just keep smashing the thrust button.
Will kill them instantly.
The skeletons are simply trampled by strafing or some other movement.
Most of the time this works.
I never use charge since that will scatter the team, and is not required with this tactic.
When there are a lots of instant respawn, you'll get owned most of the time.