We've done several collaboration projects with other Architects, and while the process has improved in the last few years, it is still painful. The Archicad-Revit translation is still not anywhere near perfect (mainly Revit's importing), and the IFC structure is still evolving.
It's important to come up with an agreement up front to properly delegate the work (and document it clearly). The easiest way is spatially, by region of the plan. The most common collaboration is to have one Architect design the Core and Shell, while the other does the Interior Build-out. Sometimes, one will take on the Site, and the other designs the Building. If it's much more interwoven than that, it can be a nightmare. One of the worst scenarios is splitting Interior Design (finishes/FFE) and Interior Architecture. The designers often want to render with the partner's model, but the appearance is substandard, and elements need to be remodeled.
Each team will need to have a BIM Manager/Coordinator who is willing to work with his or her counterpart. They will need to put in some time of trial and error to find the best workflow, especially at the beginning of the project. Good technical communication will be the key. And a lot of patience. Experiment with different file types; IFC is good, but Rhino, 3DS, STL, our even 2D DWG may be better for certain areas. Better to draw something clearly with lines and fills that to force the model to work and create confusion during construction.
Most importantly, temper expectations. Don't expect the programs, and resulting models, to match; they never will. In some cases, you may need to accept drawings that are good enough for construction, and not 100% up to your office graphic standards. Look for opportunities to use a different method than you typically use that may be more compatible. Collaboration requires compromise even when BIM isn't involved. Rendering and animations may require significant re-modeling, so limiting such work to small vignettes or a single elevation will make it more palatable, or consider creating a completely separate Visualization Model.
Phoenix, Arizona, USA
ArchiCAD 25 (since 4.5)
Macbook Pro 15" Touchbar OSX 10.15 Core i7 2.9GHz/16GB RAM/Radeon Pro560 4GB