[Daynarr]

There is a way to make a game really difficult with a minimal effort before this gets patched. All you need to do is to edit these lines in settings.txt:

Planet Value Low Percent := 0
Planet Value High Percent := 150

You can give the low percent a value of 80 or 100, and high percent (to give more variety) 200. That will make a high resource game and nullify AI stupidity at least for selecting mining colonies, simply because ALL the planets will give lots of resources.
I should also recommend playing this in 200+ system galaxy with preferably 20 Empires in it, but it will most likely cause RC errors since most of the empires will have huge fleets.

I think this is an easiest way to get a good fight from AI.