I tracked 100 pound results ONLY at the instant the pound was open, and all on a PC. NO mobile, and none if the pound was already open, even a second.
These are also the VERY FIRST pet I saw, regardless if I missed it.
From 7/19/21 - 11/18/21 - 4 months, 122 days. Included during the summer event, and Halloween event.
5 Very Rares! = 5% chance.
43 - Rares
38 - Uncommons
12 - Common & Very Common
2 - OMG So Common
The chances of getting a VR did not matter if it was 4AM or during an event, it's totally random.
2 of the 5 VR I got were a day apart! But you can see it's about 1 VR per month, or 1 in 20 pounds (remember, only at the instant the pound opens, and on a PC).
Several times I would INSTANLY miss a rare pet (but I still logged the result).
The average pet was a 2011.
2 - 2008
21 - 2009 therefore = 21% chance.
15 - 2010
20 - 2011
13 - 2012
10 - 2013
10 - 2014
6 - 2015
1 - 2016
2 - 2017
I have by species, but there were many.
29 were dogs.
20 were horses or ponies.
Only 7 were cats, +3 sitting cats.
There were 618 Very Rares in the pound = an average of 6 VR in each pound.
The most VR in the pound was 13. The least VR in the pound was 1.
I only saw ONE OMG So Rare in 100 pounds! (a Nonjewel Sundog re-release).
There were 109,278 pets in the pound, so 100 pounds = 1093 average.
The maximum pets in a pound was 1421. The minimum pets in a pound was 643.
There were 100,581 users online - NOTE: the pound refreshes every 5 minutes. AND this includes hidden AND guests.
I would check a minute before the pound opened, then again within 5 minutes after the pound opened.
Therefore the average was 1006 users online.
Maximum of 1893 online (a Monday at 1PM during the Halloween event), minimum 381 (Saturday 8AM in the summer).
The average time I was on was 2PM. I'm on Central US time.
Some days I was available to get 3 pounds in 1 day! Some days all I saw were Lost and Founds. Sometimes I was out of town or very busy and on mobile only (and NOT logged in these results).
There were an average of 1.3 pets in the pound per people online.
The most pets I saw per person was 3.2. The least was .4 pets per person.
During the summer event, there would sometime be a 1-4 second lag = all VR and most rares were already gone.
Sometimes the pound would be empty after 2 minutes.
In August, the oldest pet would be @2014 for some reason (16 out of 28 pounds).
After the Halloween event, I had a run of @2011 uncommons (10 out of 19 pounds).
Finally: I hope CS does not mind me sharing this information.