They can use the second card slot for anything else they like
22 Ichor Rats Ichor Rats is essentially a different version of Blightbelly Rat, and maybe even a bit better
As the only Trainer to make her mark, Diantha stands out from the Rainbow Secret Rare bonanza, breaking things up with her pink and white palette
The Karlov Manor mythic rare is the one that joins the list, particularly its serialized version found in Murders at Karlov Manor collector boosters featuring a double rainbow foil version of the Ravnica City treatment of the card
Victini Black White Rare from Black Bolt trails the top chase card from the set by a few cents, making it almost a co-chase with that card
However, there are two clear downsides to typal coupling, especially if it becomes too widespread