Apparently its on Gameplay Mechanics instead of design. Of which the only thing I can think of that exists is "capture them with capsules/balls" as most other Mon type games uses different objects that aren't as identical.
Considering Yu-Gi-Oh had that mechanic for monsters in defensive position, that must have expired at least 2 decades ago. Unless Yu-Gi-Oh's implementation was different enough that WotC's patent didn't apply.
Apparently its on Gameplay Mechanics instead of design. Of which the only thing I can think of that exists is "capture them with capsules/balls" as most other Mon type games uses different objects that aren't as identical.
Which is a stretch among stretches.
It was already proven times and times again gameplay can't be copyrighted anyway. This won't go anywhere then.
Patent isn't the same as copyright. Gameplay mechanics can be patented in Japan, apparently. Pretty sure there are gameplay patents in the USA too.
You can patent game play in the USA. Wizards of the Coast used to have a patent on turning a card 90 degrees. It has expired.
Considering Yu-Gi-Oh had that mechanic for monsters in defensive position, that must have expired at least 2 decades ago. Unless Yu-Gi-Oh's implementation was different enough that WotC's patent didn't apply.