Pokemon USUM (Ultra Sun and Ultra Moon) This article explains Mega Evolution. It summarizes the unlock conditions for Mega Evolution.
Table of Contents
How to activate it in USUM?
First, Unlock It
To unlock Mega Evolution in Ultra Sun and Ultra Moon, after clearing the main story, you need to go to Poni Plains and win the battle against Dexio. Winning the battle will unlock the Mega Evolution system.
Exchange BP for Mega Stones
Mega Stones can be exchanged for BP obtained at various facilities.
How to Mega Evolve
1. Battle with a Pokemon Holding a Mega Stone
Challenge battles with your Pokemon holding its corresponding Mega Stone.
2. Select "Mega Evolution"
When you battle with a Pokemon holding its corresponding Mega Stone, "Mega Evolution" will be unlocked. When you select the "Fight" command, you will be able to choose "Mega Evolution".
Important Notes on Mega Evolution
- Only one Pokemon can Mega Evolve per battle.
- Mega Evolution cannot occur outside of battle.
- The Pokemon reverts to its original form after the battle ends.
- The Key Stone is not a one-time use item.
What is Mega Evolution?
A New Feature from Pokemon X and Y

Mega Evolution is a new feature introduced in Pokemon X and Y. It is an evolution that surpasses standard evolution, activated when the "Key Stone" worn by the Trainer and the "Mega Stone" held by the Pokemon resonate due to the bond between the Pokemon and Trainer. It is also present in USUM.
Unlocked Only During Battle

Mega Evolution is a command that can only be used during battle; it cannot occur in other situations. The Pokemon reverts to its pre-Mega Evolution state after the battle ends, but it cannot revert to its original form during a battle in which Mega Evolution has been activated.
Legendary Pokemon Also Evolve

Similar to regular evolution, its appearance changes, and its stats are significantly powered up. Pokemon that have already evolved twice and Legendary Pokemon can also Mega Evolve.