YoungCha

They had mentioned a hidden group in news articles. Two of the members were at the press conference, most of the members have a decent following on social media. They also made a video for the group and a few posts on social media. Two group members appeared briefly in the first episode to promote the beanfun voting. They were ranked 1 on topic and had 20k in fan interactions (This was in June not sure what is it on now)

It's a hidden group that is not coming until later on the show if they get enough votes to appear.

Next Girlz ep 1: https://www.youtube.com/watch?v=ehFmul_u0nc (no eng subs)

Mystery Group
Cryxtal 幽靈水晶
Guardian Crystal: Phantom Crystal 幽靈水晶
Representative Colour: Grey 灰色
Tung Zih-syuan 董子瑄
Huang Zi-qin 黃子秦
Chen Pin-xuan 簡芝婷
Jian Zhi-ting 簡芝婷
Lin Shu-yun 書蘊
Chen Xuan 陳萱
Xu Yi-ni 許旖倪
Yun-jing 昀靚
Cai Cai 蔡菜
Yi-pin 伊品

Fourth Group of the show
TWINKLE BLACK 黑曜精靈
Guardian Crystal: Obsidian 黑曜石
Representative Colour: Black
Entertainment Company: SS Entertainment 星光瑞瑞
Purple 紫嫣
Emma
GuoGuo 郭郭
Katherine/Yu-hsuan 雨璇
Mila 采婕
Yi-Pei 依沛
Hanna 名慧
Chang Hsuan 張瑄
Ally/Li-An 力安

CRIMZON 緋紅魅影
Guardian Crystal: Fire Crystal
Representative Colour: Magenta 桃紅
Entertainment Company: AOA Lab
Ba Lun-yue 巴倫月
Lin Shi-ya/Grace 林詩雅
Xiang-lan 香蘭
Lian Ying 連穎
Xi Zi-qi 席子淇
Li Shan-zhen 利善榛
Tong Kai-ling 佟凱玲
Pei Jie 裴頡
C.Holly

Purple Crush
Guardian Crystal: Amethyst
Representative Colour: Fluorescent purple
Entertainment Company: ACEM
Rinii
Yia
Xiu
17 (i-chin)
Meng
Bling
Lyco
Libi

Third Group
babyMINT
Guardian Crystal: Fluorite
Representative Colour: Mint Green
Entertainment Company: Him 華研國際
Jou Yang-shiu 周楊栩
Vikky 韋喬薺
Cao Jingjing 曹晶晶 - Group's Ace
Chen Pin-hsin 陳品妡
Linlin 粼粼
Lin Chiao-hsuan/Chiu-hsuan 林萩璇
Lu Hsi-yan 呂熙妍
Chang Cheng-yun 張丞妘
Chen Yan-ling 陳言菱

Second group for the show
Sunny Parfum 日光之橙
Guardian Crystal: Sunstone 日光石
Representative Colour: Bright Orange 亮橙色
Entertainment Company: Mugen
Xiyeon (Xeline)
Phoebe 張菲比
Bonnie 蔡南荺 - ACE and Team Captain
Ashlee
Shan-shan 閃閃
You-tong 宥彤
Mayu 藤井 麻由
Cherry 陳辰瑋
Theia 鄭玉歆

First Team of the show revealed
GenBlue Team 幻藍小熊
Guardian Crystal: Azurite 藍銅礦
Representative Colour: Royal Blue 寶藍色
Entertainment Company: Ten Entertainment
Hsu YuanYuan 許媛媛
Ayeon 李娥妍
Nico
Bido
Rong Rong 容容 - Group Captain
Yu 毓
Vicky
Cai Zhen/Ayako 采甄
XXIN - Group Ace

I don't think this series is going to end anytime soon.

The show will start filming in June so the air date probably will be in June as well.

Sparkling Watermelon will air in September

This season is a different ball game from the last two seasons, there are a lot more of well known trainees competing in the show.

She's currently studying theatre at Chung Ang University

She's currently studying Media Arts and Entertainment (Acting) at Dongduk Women's University

She's a musical theatre actress now

A list of contestant for the show:
吳毓琁 - Wu Yu-hsuan
Bido
許媛媛 - Hsu Yuan-yuan
簡芝婷 - Chien Chih-ting/Jian Zhi-ting
周楊栩 - Jou Yang-shiu
Nicole/Nico
采甄 - Tsai-chen/Cai-zhen
Ashlee
李娥妍 - Ayeon
陳品妡 - Chen Pin-hsin/Chen Pin-xin
林苡辰 - Lin Yi-chen
曹晶晶 - Cao Jing-Jing
申力安 - Ally Shen
韋喬薺 - Vikky Wei
張菲比 - Phoebe
陳辰瑋 - Cherry
Xiyeon/Xeline
閃閃/陳語杉 - Shan-shan
宥彤 - You-tong
蔡南荺 - Bonnie
黃子秦 - Crystal Huang Zi-qin
董子瑄 - Tung Zih-syuan
陳萱 Chen Xuan
許旖倪 Xu Yi-ni
昀靚 Yun-jing
蔡菜 Cai Cai

Apparently they have started filming for this drama, it's won't be aired until next year though.
Edit: It might air in the second half of this year according to Pan Entertainment

Choi Hyun-wook but actual pairing might be with Ryeo-un