Voilà la technique de gamefaqs tiens.
fter battle begins, have Rikku mix a Hyper Mighty G first, and have Tidus
attack Shinryu. Shinryu will counter attack Tidus and refill Rikku´s
overdrive gauge.
If Shinryu uses claw attack on Wakka or Tidus in his turn, Have Rikku mix a
trio of 9999 when her turns is up, and have other people attack.
If Shinryu uses shining, then probably all three people will be killed, and
they will be revived by auto life. However, Shinryu will have an extra turn
before you can move, so if he uses shining again, you are dead. The only
thing you can do is to pray that if he does not do two shining in a row.
Sometimes his shining only hits two people, consider you are lucky if it
happens.
You have to keep at least two people in auto life status, mix another Hyper
Mighty G when it is needed. Only mix trio of 9999 after he uses claw attack.
If Shinryu uses eraser, then you are basically screwed. However, since
Shinryu selects his attack randomly, it is possible for him not to do eraser
at all in the battle, although the chance is very little. And it is possible
for him only doing claw attack, although I doubt if anyone could be this
lucky.
IF you can defeat Shinryu, then the biggest obstacle in your NSG monster
arena quest has been conquered!!! Be ready for the ultimate boss: Nemesis!!!