A user on a Japanese forum posted an image containing information of all the eight Isshu Gym Leaders. It seems that Iris is the last Gym Leader, a Dragon type one at that. Here's a list of the translations below.
* 1st Gym Leaders are Dento, Poddo and Koon of Sanyou City. Grass, Fire and Water are their specialties.
* 2nd Gym Leader is Aloe of Shippou City. Her specialty is Normal.
* 3rd Gym Leader is unknown as half of their name is cut off in the image but the Gym Leaders specialty is Bug and the Gym is located in Hiun City. The badge is called Beetle Badge.
* 4th Gym Leader is Kamitsure (カミツレ) of an unknown city. Their specialty is Electric, the Badge is called Bolt Badge
* 5th Gym Leader is Yakon (ヤーコソ) of Hodomoe City. The gyms specialty is Ground, the badge is called Quake Badge
* 6th Gym Leader is Furou (フロウ) of Fukiyosa City. The gyms specialty is Flying, the badge is called Jet Badge.
* 7th Gym Leader is Hachiku (ハチク) of Sekka City. The gyms specialty is Ice, the badge is called Icicle Badge.
* 8th Gym Leader is Iris of Souryuu City. The gyms specialty is Dragon, the badge is called Legend Badge.
Credits:Pokestation