Pokémon can probably have it's immense (and insane) secondary market attributed to its gambling-esque qualities. It'd be perfectly fine if people could play with decks they chose and cards were sold at a uniform price, provided the game itself is balanced - which is to say gambling elements in these things are probably by design.
So much that could be done with those. Mandating age checks. Covering at least 80% of them with warnings about gambling. Maybe plain packaging and only allowing them from behind counter or unmarked automated systems. Treat them as tobacco products.
OK, we mandate age checks. But what is the minimum age? Am I in trouble if I make a straw purchase of that product for someone else?
You can just ban them. Pass a law that says if someone buys an item the identity of which is undisclosed, and they're not happy with it, they're entitled to a full refund.