Mario 6 is a
hack of Tiny Toon Adventures.
There's really nothing special here. Essentially
what you have are Mario hacks starting with Mario
4 and continuing through 16. The early
Mario hacks lacked in creativity, so often you got a
basic hack of the title screen, Mario's name
somewhere near the health bar and Mario taking the
place of the main character. Later hacks, not in the
series 4-16, are much better.

Super Games has manufactured more recent pirates.
You should pay around $10 for a Mario hack. They
have gotten more common in recent years as
collectors have begun to tap foreign markets around
Turkey and China. Yes, Turkey...for some reason
there are a heck of a lot of Famicom pirates in
Turkey.