Some pastors feel more comfortable working with pastors of their own tradition/denomination. There is nothing wrong with this as these relationships are very important. I’m thankful for my colleagues within my denomination.
At the same time, some of my most rewarding experiences have been collaborations with pastors of other denominations. It is not that I pretend that there are no differences. I disagree with my Pentecostal friends about the role of speaking in tongues and my Presbyterian friends about infant baptism. But we agree on what matters.
I have found that our common faith in Jesus, his death and resurrection, is enough for us to work together in meaningful ways. I also find that being around others with different interpretations helps me to grow spiritually.
Beyond that, working with people of other denominations is a powerful witness. I have heard many skeptics point out that the existence of the denominations as evidence that Christianity is not true. I disagree with that critique. There is room for different interpretations just as there is room for different interpretations within science. What matters is that we love and respect one another. When the world sees Christians working together, it is a demonstration that there is a real Jesus who is worth following.
I understand that there are some traditions that put limitations on what can be done with other denominations. But as far as is possible, I encourage pastors to work with other pastors of different denominations.