reproducing a copyrighted shell would be infringement
Any part of a shell that is non functional can be covered by copyright and thus be the source of a copyright infringement lawsuit. Examples are the specific color or opacity of the Game Boy Advance and its non-ergonomic design features. Another is the Pikachu-design on the yellow folding Game Boy: those are non-functional and copyright applies. You don't need a statement or even to register that.
Do note, that many things can be non-functional parts of the design. For example on the original Game Boy there is way more space in the body than needed. As a result, the exact position of the buttons could be anywhere else on the body, so their placement might be subject to copyright - the fact that the PCB was made after the shell was designed might cut very much for Nintendo there, as it was not designed utilitarian but the electronics had to conform to the design in almost every iteration since then. But are they truly non-functional after they were populated with electronics? That'd be a battle to fight in court.
reproducing the trademarks is trademark infringement.
As explained on your other question, reproducing trademarks isn't allowed.
Design patents expired
For any part that is not an artistic choice (see first paragraph), a design patent would have expired. Design patents are for 14 years.
Conclusion:
To sum it all up... it's complicated and some things most definitely are illegal to do (e.g. knockoff Pikachu GameBoys), others might be ok. Also, do remember that copyright enforcement is only through the copyright owner suing, and Nintendo, while having a reputation as a very hard litigant, might not publicly pursue every infraction of its rights for the backlash it might cause.
