I am using a battery circular saw to put some rabbits in 2x4. How would anyone else do it? Doesn't seem like a bad way just wondering if there is a better way.
Like the others have said above, A table saw with a dado blade would probably be my first choice. Second would be a router with a board clamped to it as a guide. Hand tools would be a router plane.
Depends on how long of a rabbet you're cutting. If down the length of the material I'd use a dado in the TS. If just across the end I'd use a handheld router and guide.
Many ways to skin that cat, depends on the equipment you have. Don't look like your doing fine furniture, so if you have a sliding miter saw, adjust the blade height to the depth of cut you want, then make as any passes as required...