The most effective scenarios I have seen played out in such situations–and pastor changes are always difficult–go something like this:
Pastor meets with all leadership, including, and first off, staff, PC and FC (Parish council and finance commission) and lay volunteer leadership of ministries and apostolates. When he is done with the parish he does the same with the school, if there is one.
Letting them know what he is doing and why, he “fires” everyone, paid and volunteer, in order to invite the Holy Spirit to guide direction, parish mission, and those who serve by leading ministries. He invites everyone to reapply for their current position, with a CV and updated resume, reminding them to highlight all their current contributions, and especially where they have grown their skillset and experience through their ministry. This is an affirming way of doing it, and they way they respond will tell them most of what he needs to know about who to keep and who to let go.
He does this in an atmosphere of acknowledging and affirming their gifts and contributions, and encouraging them personally, and as ministries, discern the direction in which the Holy Spirit is leading them at this time. He does this while catechizing the parish in the charismatic gifts (those given to individuals by the Holy Spirit to build up the Church–teaching, preaching, administration, service and so forth.)
It is critical he first builds a pastoral and administrative staff who share his vision, and the most effective pastors do this by inviting them to share their views in the context of vision and mission for the parish and for their ministry. He does it collaboratively without ever relinquishing or downplaying his own authority. He demonstrates that his decisions are made in prayerful discernment guided by the Holy Spirit, not as exhibitions of power.
The process is educational for him because he quickly learns who the “in crowd” is, the SSP (Same Six People who seem to run the show). The genius pastor does what business leaders do, creates VPs and puts them in charge of “nice to have but non-essential” endeavors that “need their unique experience and leadership qualifications.” That clears them out of their current entrenched positions to make room for the new leadership the Holy Spirit has been preparing all this time.
He also learns how the staff interact with each other, and with parishioners, and where the trouble spots are there. All paid employees know, or ought to know, they are employees at will and the wise parish or diocesan employee will have his resume, letter of resignation, and letter of intent to re-apply for his position, ready when a new pastor comes on board. His first priority is to get his staff behind him on the same page, eliminate from the outset sources of conflict and back-biting, and then start with a new PC and FC. He hand picks his FC but allows the parish to nominate and vote for PC, publicly after all Masses one weekend, with the guidance of the Holy Spirit actively invoked.
during this “shakedown” period the pastor if he is wise discerns who needs to move on and move out, and does this by encouraging them to explore new directions for themselves, and sometimes (not always) this necessary pruning can be done without hard feelings, resentments and backlash as the individuals involved are guided to see the action of the Holy Spirit in their movement as progress not rejection.