“Tell Archippus: ‘See to it that you complete the ministry you have received in the Lord'” (Col. 4.17)
Colossians was written to the church whom Paul previously ministered to and no pastors are mentioned. If the Colossians did have a pastor, it was probably Archippus who was located in Laodicea, it seems. The churches of Colossae, Hierapolis, and Laodicea were located relatively close to each other with the Colossian Epaphras probably being sent to Paul on all their behalf to support him while in prison.
Epaphras was also interceding to God for the churches and Paul writes to commend his ministry and assure the Colossians of his benefit to Paul (see Col. 4.12-13). It also seems that Epaphras was somehow also imprisoned at the time of writing and Paul wanted to vouch for him that he was not misbehaving on his mission (Philemon 23). Perhaps Paul was anticipating his release, as well as his own, when he wrote the wealthy and devout Philemon to prepare a guest room for him (Philemon 22).
Archippus is called a “fellow soldier” in Philemon 2 and is probably the designated pastor of the three churches in that area. This would involve a circuit ministry where each church would, in turn, be served by him. This may have worn on Archippus, as can be imagined, and, therefore, Paul tells the Colossians to encourage him to fulfill his ministry in Col. 4.17.