Plugins legality

[inventore]

I recently saw on this forum many LackeyCCG plugins of famous card games, like YuGiOh or Pokemon. My question is: are they legal?

[mathman1550]

My take is that if I own the cards in real life, this is totally and utterly legal because I am just playing the game I own, just not in person.

If I don't own the cards I use on this program, but I do own a large amount of cards of that game I could argue that I am trying out those cards, and using them will make me more likely to buy actual cards to use in real life decks that I play with my friends.

If my opponent(s) have the cards in real life, this is the same as borrowing those cards, so totally legal.

If I don't own any of the cards and never plan to buy any and my opponent(s) also do not own the cards and never plan to buy any, the legality may become iffy. I'll let someone else address this situation.