What If Ash was in Pokemon Horizons?

The Three Explorers

Ash and Liko follow Squawkabilly outside, Roy, Dot and Friede seeing them and gving chase as well. Squawkabilly stops in the kitchen of the Brave Olivine, where they also find Diana herself.

"Grandma?!" Liko eclaimed, the others behind her wide eyed, "What are you doing here?!"

"Well, your mother told me that you all were in Kitakami, so I rode Arcanine here." Diana began, "I needed to reach you, cause I have new information on Lucius!"

"Really!" Ash beamed, "What is it?"

"Well, Liko's gotta earn it!" Diana replied, "In another battle! What do you say, Liko?"

The group look to Liko, who after some thought, nods determinedly. The group head out to the Wing Deck to watch the battle. The rest of the RVT joining them.

"This time, we won't hold back!" Diana said, Arcanine taking the battlefield. Liko thinks about the last battle, remembering it took her and Roy working together to land just one hit. But she and Floragato have grown since them, they'll win. Even if Fire is strong against Grass.

Floragato starts off with Magical Leaf, and Arcanine avoids it with Extreme Speed, which Liko has Floragato take head-on so Magical Leaf curves around and strikes Arcanine anyway. Arcanine follows up with Flamethrower, but Floragato dodges it and strikes with Acrobatics. Liko cotinues that battle pattern, aiming to damage Arcanine slowly overtime.

"It's incredible how far you two have come!" Diana proudly said, before her face hardens to a stern frown that gives Liko a bit of a shiver, "But it won't be enough! Flare Blitz!"

Arcanine releases a burts of flames, Florgato tries to move away, but is grazed by the attack. Floragato gets back up and lands a Sucker Punch point blank onto Arcanine, canceling another Flare Blitz. But getting hit by Sucker Punch activates Arcanine's Justified, giving it a strength boost.

Liko's anxiety spikes, realizing her indrect mistake. She bounces back and Terastallizes Floragato, Diana calls out Flare Blitz, and Liko looks for an opening so that Magical Leaf wouldn't immediately burn up. She spots Arcanine's feet, "Perfect" she thinks, as Floragato fires the attack, maoing Arcaine fall down. Liko then has Floragato fire an even stronger Magical Leaf, defeating Arcaine.

"Wow," DIana said, returning Arcaine. "You've improved so much." She added, smiling.

"Yeah," Liko replied, "My friends helped me a lot during our Terastal Training" gesturing to Ash, Roy and Dot. Ash and Roy beaming while Dot gets flustered and avoids Diana's eye.

The RVT go into the conference room, Diana starts showing what she found. Starting with an old photo of her and her friend, Hamber. Who she reveals found out was part of the Explorers back when they broke into her castle. Shocking the others, then she adds that Lucius first founded the Explorers, surprising the RVT again. 

"That's why I left," Diana stated "To find out the true origin of the Explorers."

The RVT lean in, wanting more, so Diana starts talking "I visited towns Lucius wrote that he visited. Spoke with the elders who knew him. They told me a lot, and gave me this."

Diana pulls out another old photo, showing three trainers together. "These were the founders of the Explorers,  Lucius, Rystal and Gibeon." Diana said. 

"Well, I heard the name Rystal before when we found Kleavor, but I have no idea who Gibeon is." Friede said.

"I think we might know." Liko piped up, looking to Ash, who nodded.

"When we were trapped with Amethio, he told us about him." Ash started,

"He's the leader ot the Explorers, and his grandfather." Liko finished.