NEVER use scaling, it doesn't help them get out of their downward spiral.Vanilla scaling is pretty horrible. AI is basically as bad as Ensign... They don't have bonus at beginning and once they get bonuses, they suck so hard anyway that this won't matter. I've tried "Grand Admiral+Scaling" and "Grand Admiral+Scaling+Advanced start on everybody" and each time the AI was a joke. Commodore and above on the other hand can easily kill you if you are unlucky and have a strong neighbor that hates you. 50%+ bonuses on all jobs are pretty insane... I mean they get those bonuses on every step of a resource chain.
- Produce minerals: 150 instead of 100
- Produce consumer goods: 75 instead of 50, and still have 50 minerals from the last bonus left
- Science: 150 each instead of 100, and still have 25 consumer goods and 50 minerals additionally...
(same for a lesser degree with alloys)
And they seem to go pretty crazy on alloys with those bonuses, create a huge fleet at the beginning. Though if you survive that, they horribly fail in expansion and (for some reason I don't know) science and also don't update their ships. Thus the game will become boring later nevertheless...
Thus, IMHO the only way to currently get a challenging game that isn't pure luck in what neighbors you get is using one of my Dynamic Difficulty mods. There you get set Captain as starting difficulty (to make sure the AI does not instantly fail in their economy as they do on Ensign) and do a scaling starting from there. Or increase/decrease the bonuses manually if stuff becomes too easy/too hard.
I wish there was an option to set "what year scaling finishes" seperate from "end game start year" because the Crisis ends up kicking their butts if you turn on scaling.