So glad the Predator is finally a guest in a fighting game, particularly one as violent as MK. Anyway, on to my ideas.
The Predator's thermal vision should factor in some of it's intros when the opponent talks, and their voices should be distorted, just like in the movies. It's X-ray should also be thermal, maybe we could even see it breaking it's opponent's bones in first-person.
The Predator should mimic MK characters in some of it's intros with it's recording device, like using Jade's voice and/or Sindel's to antagonize Kitana, tell Scorpion to "get over here!", and replay Shao Kahn's taunts from MK2 and 3.
Every designs from every movies should be in as alts.
The helmet should be removable at will, and it should get knocked off during X-Rays and alities.
Now, variant ideas below:
Classic: Based on the first two movies. Adds the speargun and the missile from P2 that upon hitting the opponent, burns away at them temporarily.
Serpent Hunter: Based on the Alien Vs Predator movies. Adds the shurikens, the disc being the enhanced version, the net, which unlike Cyrax's hurts the opponent, and the Chopper Predator's very large wristblades. Chopper was the first Predator to die in AVP.
Super Predator: Based on Predators. Adds the hounds, the falcon and invisible net traps.
The shoulder cannon, the staff and the cloaking should be available for every variants. Players should be able to switch between the wristblades and the staff at will, even combine both for combos, and the shoulder cannon should be able to lock on the opponent, allowing players to fire it whenever they want during the match.
Some more ideas coming up.