Is GPL-2.0-only compatible with MPL-2.0?
Yes.
MPL-2.0's secondary licenses include GPLv2+, so MPL files may be combined into a GPLv2 work unless marked 'Incompatible With Secondary Licenses'. Result license is the more restrictive of the inputs. You must satisfy every input license's notice and source-offer terms. Verify pairwise compatibility first.
Resulting work's license: GPL-2.0-only
General guidance, not legal advice.
Obligations when redistributing as open source
- GPL-2.0-only: retain the copyright notice and license text.
- GPL-2.0-only: state significant changes made to the code.
- GPL-2.0-only: provide complete corresponding source of the combined work.
- GPL-2.0-only: the combined distributed work must be licensed under GPL-2.0-only.
- MPL-2.0: retain the copyright notice and license text.
- MPL-2.0: state significant changes made to the code.
- MPL-2.0: disclose the source of modified MPL-2.0 files.
- MPL-2.0: modified MPL-2.0 files must remain under MPL-2.0.
Other distribution models
The verdict is the same under every distribution model; the obligations differ. Check this pair in the tool to switch models.