How much would take him ascend to 9-D because unless is something relatively fast I don't think it would come to play in the fight.
The babyfication was something that BB used against Kingprotea and Kingprotea is made of a Imaginary Number space which is basically a higher dimensional plane with various effects (you can see it in the powers section to get more details). BB cursed Kingprotea with it to counter her infinite growth, so automatically when Kingprotea reach 20 years she return to be a baby both physically and mentally. Servants mind/information/concept is in their soul so the curse should also be able to affect his mind, you can check
servant physiology, servants are also immortal but still affect them.
If his haxs aren't also 9-D then Kingprotea would resist them.
And if he have a 9-D being that can fight for him would it be listed in the tier and attack section?