Flounder would definitely be there. He's Ariel's loyal friend and would be by her side to help face Ursula again.
Sebastian could also play a major role. He has a lot of knowledge about the sea and its rules. He might use his musical talent in a different way this time, like using his singing to disrupt Ursula's magic spells. Also, Prince Eric could be important. He might be on land at first, but when he realizes Ariel is in danger, he finds a way to come to the underwater world to help her, using his human skills and resources to fight against Ursula's return.
I think Triton, Ariel's father, would be a crucial character. He has great power as the king of Atlantica. After Ursula's return, he might have to make some tough decisions, like whether to trust Ariel's new ideas on how to deal with Ursula or stick to the traditional ways of the underwater kingdom. And perhaps there could be a new mermaid character, a young and brave one who idolizes Ariel and wants to help in the fight against Ursula, bringing some fresh energy and new abilities to the story.
Chapter 328, "Unexplainable Unease, Jade Dew Stone, Li Xuanling's Panic (Part 4)", is the clearest early answer because it turns Deceitful Monster's situation into a concrete plot event. The setup is I don't have the ability to control the Deceitful Monster., but the pressure keeps building through The more this White Dew Gu knows, the more schemes it has..
Chapter 331, "Zhu Shun, Huang Tianxi, the Third Cold Yuan Banquet of Great Xia, and Xia Yuzong", is the clearest early answer because it turns Huang Tianxi's situation into a concrete plot event. Early on, Upon hearing the excited sound of his nephew running towards the.... By the end, Compared to you, he's far behind!" Zhu Shun wasn't saying this to....
Chapter 264, "Supplies Delivered, News from Long Mountain", is the clearest early answer because it turns Wu Tianxing's situation into a concrete plot event. Early on, Second Year of Great Xia, May 20 Wushuang Giant Stone Camp, Top Floor.... By the end, Wushuang and Hanqiong still have defense duties, so Xia Chuan took....
Chapter 304, "The Defeated Longyou Army, Xia Army Cannot Escape, Holy Tripod", is the clearest early answer because Cold Resistance Level gets a payoff that changes the stakes. Early on, In just a moment, roars erupted continuously from the direction of.... By the end, As soon as Li Xuantiang spoke, the crowd immediately wore relieved....
Chapter 76, "Who knows if there is poison inside", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. The chapter turns that into something concrete by moving from Thinking of this, the aunt repeatedly praised, "Girl, hearing your...
Chapter 304, "The Defeated Longyou Army, Xia Army Cannot Escape, Holy Tripod", is the clearest early answer because Great Xia gets a payoff that changes the stakes. It opens with As the two armies distanced themselves, the underground main zone... and closes on How are the soldiers' conditions?" Just earlier, after the Teng Jiao....
Chapter 298, "Hou Jing Surrenders, White Abyss Falls, Zhaoyang Changes Its Banner (Part 4)", is the clearest early answer because it turns Wu Ningyuan's situation into a concrete plot event. The setup is I am Wu Ningyuan, I am willing to surrender, please show mercy." Chen..., but the pressure keeps building through Not only Chen Yingba, but Peng Bo, Wu Tianxing, and even the later....
Chapter 324, "Early Drills, Surge in Cold Resistance Level Members", is the clearest early answer because Zhou Yuan finally turns buildup into a real advancement. The chapter turns that into something concrete by moving from After Xia Chuan's two-month-long transformation, the outer city has... to If you want to die, go ahead, but I'm not joining in your madness."....
Chapter 191, "Sister, Jiang Cheng is bullying me!", is the clearest early answer because it turns Shen Lan's situation into a concrete plot event. A useful checkpoint is the way the scene starts with This change made Jiang Cheng extremely uncomfortable.
Chapter 341, "Moao's Nine Towns, the Inspection System and Zhenyu, Li Hu and Hong Yuru", is the clearest early answer because it turns Li Hu's situation into a concrete plot event. The setup is Lu Yang struck the nail on the head, and Zhao Hu and Zhu Shun..., but the pressure keeps building through Yang Ning and Li Hu, they are both from Beishuo Town..