Blimey what a mess!!

Without the added influence of people the dynamics of such a large number of dogs running together will be volatile at times - this would be the same in a wild pack or a pack of domestic dogs. Add in the people and sooner or later a situation will arise that people and dogs react to differently (because we are different species and look at life in different ways) and WHOOSH!

Humans and their dogs have very different relationships - some very well behaved dogs believe that they are the leaders of their family pack - some very "badly" behaved animals believe that they have no leader and are not up to the job themselves so try bravado as a way of coping (it is a fear thing - the tougher I act the less likely the others are to realise I don't know what I'm doing) hence the peeing on people dog. His owner simply does not understand the animal and the animal doesn't understand him, the other people and probably the other dogs. Most people would class this dog as a very dominant animal - it may be, but I suspect that it is a poorly socialised, poorly handled, very insecure dog.

Poodle person is in the same league - no understanding at all about pack dynamics, social interactions (between dogs or people!) or what the dog is saying before it acts.

This is the major problem with dog parks - you can not anticipate who is going to be there when you turn up.
Is there anyway that your regular friends and you can arrange to meet and go for a walk somewhere else. This not only restricts the dogs and people who are invited but also ensures that you have a manageable number at any time. The best bit for the dogs is that they have other things to think about rather than making the territory their own and defending it - lots of new things to smell, look at and discover instead of concentrating all attention on each other.