Interesting premise! I think the AI is too hard to start out with, it's ok to have it teleport and have triple jump, but when the user is just starting out that's very intimidating. I would give it a slow telegraphed teleport to start out with (have like a portal appear before the enemy teleports) and make it run slower and occasionally stop/slow down for a bit to start. Then as the player collects more diamonds the AI get's faster and it's abilities become more dangerous. This gives the user a few easy wins to keep them engaged while not reducing the overall challenge you've devised.
I would also suggest putting one diamond in plane view of the starting position, allowing the user to have an initial target, and understand that collecting the diamonds is the goal.
Overall interesting platformer, and I'm impressed that you were able to make an AI for the users to play against!