I like the idea, but there is 1 enormus big huge issue with this besides the obvios onces that this will not happen ever.
You know tha game has a lot of players? When I say a lot, that is something. So for a thing like this, that you sugested, that means every player that make at least 1 copy of no matter what rarity quartz, will ask for the exchange mon, and this means it need to be made manually, from player to player, and can u think how much time it will take for let's say 2 members of the DHT to send those cards to each individual player who wants a specific mon? Maybe 6 months? Or 8?
And the rest is history. But I like the idea, and it will be much eazy if the idea was this way, insted of choosing from all the digimons, they can make a list of 2 holy 2 nature 2 dragons 2 dark and 2 knight sp+ and letting players evolve that sp+ in one of the 10 options we get.