I would say at 135lbs Yan's power is exceptional. Thus far his takedown defense seems to be as well in how dominantly he was able to stave off Jimmie Rivera's, Faber's and Sterling's takedown attempts (not a bad line up) and he improved after the Magomedov loss and showed stellar grappling in the rematch he won. Its a little too soon to tell about cardio but after rounds 2, in 3 and 4 vs Aldo and Sterling he became more dominant so it looks like he is strong late too and has a good tank.
He certainly has weaknesses, he's not the quickest and he likes to punch a bit outside of boxing range and throws loopy often, if you watch the Rivera fight, Rivera was outlanding Yan, beating him to the punch and somewhat the better man on the inside boxing. But he is super strong with no real holes.
Dillashaw is old and had a long layoff, he went tooth and nail with Sandhagen and inclined to believe his wrestling strategy is a poor idea vs Yan. I feel like Dillashaw is quicker, has way better setup's and way better defense and headwork and footwork. That said, Yan's like 27, has huge power and is rising to his prime. Dillashaw is chinny, hold and lost years, I dont think Dillashaw wins but I think he can give Yan trouble.