Originally, this was strategy that I have developed for my Cloud. But he will be part from a video that I'm preparing atm, so I decided to post Yuffie as standalone video.
Emerald has 1000k HP. Yuffie can do ~150k dmg/limit, so we need 7 limit breaks. I know - this can be done with 1 limit +6 counter=mime but this takes a lot of times to grow the materias, so I did it with 1 limit + 2 times 3 counter=mime.
This strategy worked perfect because I could utilize the 4 Hero Drinks the same way - 1 + 3mimes.
So during the fight I throw 1 Hero Drink and 1 limit, everything else is done by the counter ^^
* No need for level 99
* No need for max stats
* No need of Gold Chockobo/KoTR
* No need of full limit break bar (you need to take at least 3 hits)
I used some extra protection - Sadness, Ziedrich, Touph Ring, but if you are higher level or with better stats you don't need all of this. BTW don't use Mystile, because the chance for miss is high and we don't want that :D
Please rate, comment, check my other FF videos and subscribe (I have more videos with Emerald/Ruby coming and later this year FF9/ FF5), but most of all - have fun!