as I don't know how the code operates in the game, my guess is that if it's implemented, it will be sequentially, otherwise I'm not sure if you would get two twiceratops with an unsummon. while the twiceratops I suggested would be "at the same time" as ideas goes, is not set in stone (plus there could be balance reasons I don't know about).
too bad, it's the only dinosaur card there, while there are possible alternatives like the TurboRaptor or the Tessaurus Rex, they wouldn't be probably as interesting as this little fella.
Edit to your questions.
Draft would give it +3/-3 and no airborne which is what people would expect it to do.
and with Jetstream it would get on the first activation +3/-1 plus airborne, and on consecutive activations would net +6/-2.
Edit 2: Dragontom graciously suggested another possible take on Diffusion:
2
permanent. 1
: If target creature's HP is bigger than its attack, it gets -1|+1. otherwise, if it is smaller, it gets +1|-1. Increase all numbers on this ability by 1.
Edit: Concerning the new addition of Power leech, the idea was a creature that could steal "power" to generate chaos seed (or upgraded version) on the owner hand, I envisioned the creature like a kind of hybrid between the parasite and shadling (and that's why the stats are similar)
However, if instead of "hurting" the opponent creatures to steal their hp, I also thought of a possibility where the creature "damages itself" to give you the cards, in which case it would be a medium or big creature in cost (like 6 for a 4/15) and by entering play with "purification counters" it can "regenerate" the hp part of the cost of activating it's skill (not so for the strength part but that's the risky aspect).
Edit 2: From feedback obtained on the discord I got suggestions from the Claysmith to change it. as follows "if at least 1
quanta was paid create..." and regarding "stacked permanents" it only gets 1 stack (so if you pick pillars or similar you only get 1 pillar that lasts for 1 turn.
Edit 3: For Lightning emperor suggestion, a possibility could be switching the elements around (aka being an aether creature) and the unupped could be dealing 3 damage (spark throwing) while the upgraded could throw lightnings.