SIAD said:
How strong were they 2 10,000,000 years ago?
South Kaioshin ought to be as strong as himself when he fought Boo, given it's never implied he was able to become any stronger since fighting Moro. I'd say that South Kaioshin Boo = Pure Boo + South Kaioshin in power, which via-scaling would have me place South Kaioshin in between Evil Boo and SS3 Gotenks.
Dai Kaioshin would probably be stronger than SK given his better performance against Moro. With Moro having referred to Current Boo as having gotten weaker than last time, Dai Kaioshin with God Ki should be above Current Boo by some degree.
How strong were they 5,000,000 years ago?
South Kaioshin - Same as before.
Dai Kaioshin - Probably at least equal to Good Boo, given how he comprises that Boo's very existence. He could be far stronger though when considering his consciousness in Boo wasn't active until the current arc, though he'd likely be weaker than Pure Boo or at best slightly below South Kaioshin.
How strong was Mr. Boo before he was hypnotized?
Same as he'd been throughout his previous appearances, given he's not implied to have gotten any stronger since the Boo Arc.
How strong is Mr. Boo (Current)?
Significantly below PSSB tier, though far above SSG tier. I'd say he ought to be at the top of SSB tier, comparable to the likes of fatigued Base Vegetto or closing in on the weakest of PSSB tier such as initial LSSJ Kale.