The only thing is that before Oichi has her warrior transformation her best link is with jigglypuff only. So when you evolve it the max link is gonna be 90%. But when she does warrior transform it'll go back to max 100%. It won't change your current link unless its above 90% which if you were that high already you would have her evolved since Oichi transforms with a link of 55% with jigglypuff or wigglytuff and one other condition which you would most likely have filled at that high of a link level.
Does it even matter? You wont be getting to 100% link unless you grind like crazy and who wants to do that? Since link doesn't transfer between episodes while evolutions do.
The Official Odin of the Shin Megami Tensei IV board. Me and polite have never been on close terms.