Well, you have to settle on some common exchange format like PSD, TIFF or DNG or use the same tools like Photoshop and Lightroom in the same versions. It's simply in the nature of Raw files. It literally means "raw" data from the camera that still needs to be processed to produce editable pixels.
In general CR2s and NEFs will open in Adobe software as long as it is newer than the camera models involved.
If your friend is using Nikon software then it won’t work with Canon raw files.
What is the software brand and version situation on both sides of the transaction and what camera model(s) are you sending raws from?
Try Adobe's DNG Converter. Set compatibility to the oldest commonly supported version of Camera Raw and cross your fingers your friend can open DNG files instead.
Otherwise, you're stuck with JPG and TIFF.