Rather, multiple companies make games for one console. If you buy those games not made by Nintendo from sources other than Nintendo's shops then you can boycott Nintendo without boycotting non-Nintendo game developers.
I believe developers on consoles always pay the console manufacturer a fee per-copy, so not so much, but that's probably the way that pays Nintendo the least.
EDIT: Just remembered the second hand market. Carry on.
EDIT: Just remembered the second hand market. Carry on.