Ai Xing, Chen Huan, and Chu Xin kept attacking Eternatus's defenses, trying to find an opening. Fortunately, Chen Huan's Vespiquen controlled enough Combee that they soon found a gap.
Once they found the opening, things became much simpler. The three commanded their Pokémon to strike it with their strongest moves, instantly breaking through Eternatus's defenses.
Chu Xin and the others had interrupted Eternatus's energy absorption. Eternatus had never expected its defenses to be breached. After all, that defense could withstand several attacks even from the legendary Zamazenta and Zacian.
That defense had consumed a great deal of Eternatus's energy, and even it could not deploy it again so soon. Eternatus could gauge the strength of the Pokémon attacking it at a glance. Aside from the few Dragon-type Pokémon that warranted caution, the others were still weak and completely incapable of stopping it. That was why Eternatus had chosen to hold them off with that defense.
In its eyes, a barrier formed from Dynamax Energy was more than enough to stop Chu Xin and the others.
When the Dynamax barrier shattered, Chu Xin and the others finally felt Eternatus's power firsthand. Vast amounts of energy flooded the cave beneath its immense body.
That energy stirred memories of its obsession in the Dragonite within Xiao Wu. Enraged, Dragonite took control of Xiao Wu and fired a Dynamax Cannon straight at Eternatus.
The Dynamax Cannon, wreathed in blue flames, struck at Eternatus. After dodging Xiao Wu's attack, Eternatus stared at Xiao Wu in shock. Another Pokémon had actually mastered Dynamax Cannon?!
"Garchomp, Mega Evolve!"
As Ai Xing called out, he gripped his Key Stone. White energy poured from Garchomp's body, and before everyone's eyes, Garchomp evolved once again into Mega Garchomp.
After Mega Evolution, Mega Garchomp's presence was powerful enough to rival Eternatus's.