In general 2 hours is way more than enough to transfer at HKG, but CO99 is almost always late. Sometimes 15-20 minutes, sometimes an hour or so. My parents, my cousins and myself fly it a dozen or more times a year and I usually keep check of its time. It's hardly ever on time for one reason or another - whether it's EWR weather, equipment shortage, waiting for connecting passengers or something else. Since the plane sits at HKG for 15 hours after arrival, CO doesn't really hustle to get this flight out on-time.

Having said that, 2 hours should still be enough.