Rock Tomb + Rock Slide. Together, they almost completely sealed off Cubone's ability to move forward.
But Cubone wasn't just a "melee" fighter; it could attack from range too.
Spotting a gap between the Rock Tomb pillars and the falling rocks of Rock Slide, Cubone zeroed in on Lairon's position and hurled its Thick Club without hesitation.
The club howled through the air, spinning between the two attacks and striking Lairon right on the head with pinpoint accuracy.
Thunk!
One hit.
Thunk!
A second!
Ruuuuumble...
The Rock Slide came crashing down, burying Cubone under a cascade of boulders.
Dust exploded in every direction, blocking everyone's vision. But soon, a voice rang out from within, full of energy.
Meanwhile, two visible dents had formed on Lairon's steel head… just looking at them made your own head hurt.
Ground-type suppression was overwhelming. Under the quadruple effectiveness, every one of Cubone's attacks rattled Lairon to its core.
"CUUU"
With a loud cry, Cubone climbed out from the rubble.
Its sturdy skull had protected its vitals. The falling rocks had only left minor scrapes.
Grabbing the Thick Club that had returned to its side, Cubone didn't hesitate… it threw it again.
Bonemerang. Encore!
A green barrier flared up.
Lairon, still dazed, forced itself to stabilize. But it didn't dare take another direct hit; it quickly used Protect.
Bonemerang failed to land. Cubone, still running, caught the returning club and kept charging at Lairon.
By now, Lairon's movements had visibly slowed. When the Protect faded, it tried again to cast Rock Tomb to stop Cubone.
But it was dodged every time.
Seeing Cubone about to smash its head again with that club, Lairon finally lost its patience. Its body lit up with orange energy as it charged in a full-body tackle.
Move: Take Down.
Boom!
Take Down and Bone Club clashed head-on. Cubone was knocked backward again, tumbling twice before it stopped.
Lairon stayed rooted in place, eyes glazed over.
Only after Cubone slowly climbed back to its feet did Lairon finally stumble, then collapsed with a heavy thud, eyes spiraling.
"Phew…"
Haruki let out a long breath, feeling immensely relieved.
If not for the massive type advantage, just that Rock Tomb + Rock Slide combo alone would've buried most Pokémon alive.
Even with the advantage, Lairon had taken two full Bone Club hits and one Bonemerang before it finally fell. No wonder it had such a reputation for ironclad defense.
Beldum zipped over to Cubone's side, circling around excitedly like a bouncing bell.
Pshi~ pshi~
Haruki sprayed Potion on Cubone's wounds, then gave a proud thumbs up.
"Nice work!"
Cubone rested its club on its shoulder, nodding casually, but its shining eyes betrayed how thrilled it was by the fight.
Nearby, Lairon had already been surrounded and protected by the remaining Arons.
Haruki looked at the bristling Aron horde, hesitated, then pulled out two Oran Berries.
"Give these to your leader. It'll heal faster."
He placed the Oran Berries on the ground, then backed away a few steps with Cubone and Beldum.
The Arons remained wary and didn't come closer, but as Lairon still hadn't regained consciousness, one brave Aron finally stepped forward.
It picked up an Oran Berry and ran back to Lairon, slowly feeding it piece by piece.
This time, Lairon finally stirred. Its eyes opened and immediately turned toward Haruki's group.
Seeing they hadn't approached -and had even backed away further- its eyes flashed with brief relief.
Lairon ate the second Oran Berry, regained a bit of strength, and slowly got to its feet.
It turned and called to one of the Arons nearby, then led the rest of the group back into the shadows.
The Aron it called happened to be the one that had stepped up to grab the Oran Berry.
It looked back at its clan, then at Haruki, and slowly walked to the side… quietly demonstrating Iron Head.
"You two go and learn… and don't bully it on purpose."
Haruki gave the order, though mostly to Beldum. He'd already figured out that this Beldum wasn't nearly as innocent as it looked. Its tiny head was always scheming something.
---
And so, training for a new move began.
For Cubone, Iron Head was a solid fit. Steel-type coverage expanded its striking options and gave it an edge against Ice- and Fairy-types.
(Note: Should I stick with this format: Xx- and Yy-type, like the wiki, or Xx/Yy-type)
Iron Head didn't rely directly on the Thick Club, but it still benefited from the damage boost, letting Cubone deal double its base Attack.
Haruki didn't know why, he just knew it worked.
For Beldum, Iron Head was even more fitting.
Its whole body was basically a steel head, and its go-to strategy had always been to charge forward and bash things.
Previously, it had thrived in the cave using nothing but Take Down. Now… with Iron Head -a same-type move- it would truly take off.
Haruki gave a moment of silent for the other Pokémon in the cave.
---
Just like that, three days flew by.
Training was meant to make them stronger, and learning Iron Head was no less effective than battling nonstop for three days.
In that time, Beldum was the first to master Iron Head. Its proficiency seemed almost innate; smooth and natural from the very start.
Cubone, on the other hand, made slower progress. At this point, it only had about a 50% success rate when trying to use Iron Head.
As a pure Ground-type Pokémon, Cubone had an easier time learning Rock-type moves. Steel-type techniques were a tougher hurdle.
Haruki didn't force it. He simply adjusted Cubone's meal plan, temporarily including more Steel-type Pokéblocks to help it internalize the new energy.
The rest would come through battle.
After all, that's how Ash -the fool- trained, didn't seem too ineffective.
Bidding farewell to the now-aloof Aron group, Haruki continued exploring the cave with Cubone and Beldum.
The cave's tunnels were a maze, and even with Beldum leading the way, many areas were unfamiliar to it.
As Beldum explained, it had only recently hatched and hadn't had time to explore much yet.
Haruki wasn't in a rush. He used the simplest method: go from left to right, explore one path at a time, and mark each as they went.
If they encountered Pokémon and could win, they fought. If not, they ran.
Any valuable Pokémon were captured; those could be traded for the resources they needed to survive.
Unfortunately, the Aron clan was too tightly bonded. And since Haruki had already made a promise, it wouldn't be right to catch any of them now.
Otherwise, aside from his own Shiny Beldum, the Arons were probably the most valuable Pokémon in the entire cave.
Of course, because Haruki had never captured a single Aron, there was no fundamental conflict between them.
If he had -even once- those hundreds of Arons might have swarmed him. And unless Cubone collapsed the whole cave with Bulldoze, there'd be no way to hold them off.
Arons were timid and cautious by nature, but when pushed to the edge, those mild Pokémon could become truly terrifying.