You can unlock Shinryu in the Monster Arena by capturing two of each of the three underwater fiends at Mt. Gagazet. These fiends include Achelous, Maelspike, and Splasher.
HP: 2,000,000
Because Shinryu is an underwater creation, only Tidus, Wakka, and Rikku will be available for this fight, as they are the only players who are capable of fighting underwater.
You should consider power leveling your characters and obtaining the Celestial Weapons. Check out the Advanced section of the Tips and Tricks for more information. Properly leveled characters with their strongest weapons are a necessity for this battle.
Shinryu will counterattack regular attacks and will also use an attack called “Eraser.” This move has the potential to cause the Petrify status effect. This status will ignore any 
Ribbon and Stoneproof auto-abilities. So really, the only way to get around having your characters petrified and removed from the battle is to defeat Shinryu quickly.
| Ability | Description |
|---|---|
| Sensor |
“Immune to sensors.” |
 Scan |
“Immune to scans.” |
Steal:
Gambler’s Spirit (common)
Three Stars (rare)
Drops:
Wings to Discovery (common)
Dark Matter (rare)