Ash chose the Vermilion City Gym as his third challenge for two reasons: it was nearby, and it was tough.
In Kanto, four Gyms were famous for their difficulty: Saffron, Viridian, Cinnabar, and Fuchsia. According to Brock, even their "easiest" challenge levels were completely out of Ash's reach right now.
That left two more realistic options: Vermilion City and Celadon City.
Celadon was farther away, while Vermilion sat neatly on their current route. The difference in travel time wasn't huge, less than a week's detour, but the choice of order mattered.
Both Gyms were considered mid-tier in difficulty. Celadon specialized in Grass-types, which should have been easier for Ash, since he had Pidgeotto and Butterfree, both of which countered Grass Pokémon well.
But the catch was this: the more badges a Trainer earned, the tougher the remaining Gyms became. If Ash challenged Celadon first and won, Vermilion would scale up in difficulty. Vermilion was already considered harder than Celadon by default; if it became even tougher afterward, that would be asking for trouble.
So Ash made the smarter choice, head for Vermilion first, while the difficulty was still manageable.
The road to Vermilion wasn't short. To get there, they had to pass through a string of small towns. In fact, this leg of the journey was shaping up to be the longest they'd taken so far.
A week passed. In those seven days, the trio only reached one small town, where they stocked up on supplies before heading right back out.
Along the way, Ash faced plenty of Trainers on the roadside, but not once did he lose. Each night, he checked in with the veterans in his group chat, who made sure to point out his flaws and gaps in strategy. Without their feedback, Ash might already have gotten cocky.
Victory after victory was exhilarating, but also dangerous. For a ten-year-old who had yet to taste defeat, who had two badges and no losses, not even against wild Pokémon, it would have been easy to let pride swell. The only reason Ash hadn't was because he'd seen what a higher level of battling looked like.
The seniors in his group were all other versions of himself, Trainers who had grown into champions and masters in their own worlds. Compared to them, his little win streak was nothing but a first step.
That was why Ash hadn't lost himself to arrogance.
Misty and Brock, who had both expected they'd need to "bring him back down to earth" along the way, were instead surprised at his composure.
A rookie Trainer, undefeated, sharp in his tactics, and yet humble, such a thing was rare. Both of them, separately, credited Professor Oak. After all, if the man had once been Kanto's Champion, wasn't it possible that his "grandson's rival" had inherited some of that training talent?
On the road, Misty eventually brought up the question that had been nagging her:
"That Electric Acceleration move… and Pikachu with the hat. What's the deal with that?"
Even though it looked like nothing more than an accessory, Misty's instincts as a Gym Leader told her the truth, Pikachu's power had definitely risen when he wore it.
For a starter Pokémon to take down a experienced opponent, type matchups and clever tactics alone usually aren't enough. Without some form of amplification, the gap in raw strength is simply too wide.
Ash, however, kept Pikachu's Partner Form a secret. To Brock and Misty, he explained it only as an Aura Fusion, a technique where he and Pikachu synchronized, letting Pikachu draw directly from Ash's own power. That, he claimed, was the source of Pikachu's sudden strength.
As for Electric Acceleration, Ash described it as a move Pikachu created on the spot the first time he wore Ash's cap. But it only worked while Pikachu had the cap on his head, which was why Ash always made sure Pikachu wore it in crucial moments.
Out of curiosity, Misty plucked the cap from Ash and put it on herself… nothing happened. She blinked, disappointed.
Brock, on the other hand, finally had one of his lingering doubts answered. "So that's it… Aura Sphere wasn't Pikachu's move at all, it was yours, Ash!"
Even as a Gym Leader, Brock had never heard of a Trainer transferring their own strength into their Pokémon. And in truth, most humans wouldn't be able to do anything with such a gift. Trainers were, after all, just human. What power could they possibly lend a Pokémon in battle?
But Ash wasn't just human. His body and his strange abilities already set him apart. If Ash were ever to face a Pokémon himself, even a experienced one, Brock and Misty weren't sure the outcome would favor the Pokémon.
Still, that realization barely scratched the surface of Ash's potential.
Over the course of the week that followed, every one of Ash's Pokémon improved. Training sessions during their travels, roadside battles, and sparring with Misty and Brock all pushed them forward.
Pikachu climbed further into Advanced level and picked up several new moves.
Butterfree and Pidgeotto both broke into Advanced level as well, though Butterfree still hadn't mastered Tailwind, the move Ash had been hoping for. Even so, their current moves gave Ash plenty of creative options to frustrate his opponents.
And then there was Ralts.
In just seven days, the little Psychic-type had climbed all the way to Intermediate level. At lower stages, leveling could be quick, but this pace was astounding even by those standards.
Caterpie's leap from Novice to Superior had been possible only thanks to evolution, and Bug-types were known for their explosive early growth. By contrast, Pidgeotto and Butterfree had both slowed down significantly after hitting Advanced.
But Ralts was different. Still unevolved, not a fast-growth species, yet her progress was nothing short of extraordinary.
Even Brock couldn't hold back his awe. "Ralts… she's the fastest-growing Pokémon I've ever seen."
Now, with her new strength, Ralts wasn't just a tagalong. Against weaker opponents, she could finally join battles herself.