Note that this system is pretty flawed, but!
The way this would work depends on the creatures superhybrid(s). For instance, Spino2 makes a spyx, so you can trade it for rex, erliko, diplod, etc. Meanwhile, Schapotator is already a superhybrid, so it can only be exchanged with epic superhybrid DNA.
This way we don’t have people trading koolaid for diplod (easy to get, worthless, vs, hard to get, awesome) the only flaw would be that globals could be traded for exclusives, but there isn’t a lot I can do about that