I couldn't finish 'em. Looks like this's gonna get complicated.
Covered in shining scales, this celestial dragon uses Celestial Eye to boost all foes' vulnerability to light, then smites them with the blinding light of Holy Breath.
Shinryu has three special abilities it makes use of, like the rest of the dragons. Its Bite attack deals heavy physical damage to one target, Celestial Eye renders the party Light-Weak, and Holy Breath is a physical attack that deals heavy Light damage to the entire party and may inflict Blind.
There are three simple counters for Shinryu's more dangerous attacks. Ninjas can use Utsusemi to cover themselves against Bite and Holy Breath, Templars may make use of Rampart to shield the entire party from Bite or Holy Breath, and Spiritmasters may use Spirit Ward or Greater Spirit Ward to protect one or all party members from the effects of Holy Breath, if not Bite.
To exploit Shinryu's Dark weakness, one or more Arcanists with the Status Ailment Amp support ability should first focus on inflicting Poison on Shinryu, and once it has been applied, repeatedly use Exterminate to deal large amounts of damage to the dragon. The BP Recovery support ability will be very helpful, as it will provide the character with 2 BP every time Shinryu uses Celestial Eye and if its Holy Breath inflicts Blind. These Arcanists will need protecting, either by the Spiritmaster's Greater Spirit Ward and healing or by the Templar's Rampart ability.
Shinryu is the Japanese on'yomi name for Shénlóng, literally "god/divine dragon", an important ancient dragon in Chinese mythology. It is said to preside over storms and rain, and can bring disastrous drought, thunderstorms and general bad weather if it feels neglected and/or angered.
A notable difference between common Chinese dragons and a Shenlong/Shinryu is their fingers; the latter have five on each hand as opposed to four, and they are said to share the same green-blue-ish color as another mythological dragon, the Qinglong/Seiryu (lit. Azure/Blue Dragon). The Final Fantasy interpretation has four fingers on each hand.