Registeel still looked the same, but Metagross looked rather miserable...
After being tempered by the Underground Pressure Tempering Method, the metal surface of Metagross's body was uneven and dented, its form twisted out of shape.
It looked somewhat listless as well. Upon seeing Roy, Metagross weakly greeted him, then silently took out a Vitality Block and swallowed it.
A surge of life force flooded into its body, and Metagross's injuries began healing at high speed.
"How many times today?" Roy stepped forward and asked.
"Wuun. (Three times. I completed all the tasks!)" Metagross said in a relaxed mood.
Three rounds of Underground Pressure Tempering a day was the limit its body could endure. Any more than that would do more harm than good.
Today's devilish training was finally over. Metagross was as happy as a student on vacation, practically ready to take off on the spot.
"Very good. We're one step closer to challenging Ho-Oh!"
Roy encouragingly patted Metagross and skillfully fed his Pokémon a bowl of motivational soup, while using Aura Power to sense the changes in its body.
...After only two days of training, Metagross's body had become thirty percent harder than before.
This training efficiency was terrifying.
The Underground Pressure Tempering Method sounded crude and simple.
But in truth, ordinary Pokémon simply could not train this way.
First, any Pokémon that needed to breathe was ruled out. The underground was not only severely oxygen-deficient, but also filled with mixed toxic gases. Only mechanical lifeforms immune to Poison-type attacks and capable of surviving without breathing could adapt to that environment.
Second, they needed an expert capable of taking them thousands or even tens of thousands of meters underground, then bringing them back out safely.
Only Registeel could do that. It was its unique ability.
"Ninetales, please gather everyone."