Idea for a pred: one that is able to level up an unlimited number of times, something like 3/3 for 3 energy. Starts very weak but scales up. I suspect this would be a weaker scaling strategy than something like Nexxi or Mobi, given the number of copies you can have is inherently limited and it would require a big energy investment compared to those, so to make it more viable, each level could also raise their maximum capacity by the same amount, allowing them to potentially scale bigger than any other pred if you have enough to stack up. Would have some synergy with Plum and Seraph, potentially.
On the repeated proposition of pred-on-pred, while having a pred who can eat the others is understandably a no-go, having one that can be eaten by others could be valid. Basically a pred who can be "leveled up" into any other pred, transferring their stats over. Could make for a fun strat paired with a pred that removes rules from prey- basically letting that pred indirectly gain the effects from beneficial prey like Mufi, Sachiho and Angel. An option could be the ability to play them on a seated pred for a small buff, so the card isn't completely dead if you draw them late.
Alternatively, there could be some way to "pick them up" from their seat and feed them to another seated pred, but that would probably be finicky to implement.
A switch prey could also be possible, one that gives more points for each other prey in the belly (to represent them "eating" the other occupants).