>>19023365307.3a A Pokémon is leveled up by playing the Level Up card on top of a Pokémon in play whose card name matches the
“Put onto [name]” text on the Level Up card.
307.3b A Pokémon that levels up retains all damage from its previous stage. Any other modifiers are removed (402.2).
307.3c Only an Active Pokémon may be leveled up.
307.3d A Pokémon may not be leveled up unless it has been in play continuously since the start of its owner’s current turn.
307.3e A Pokémon may not be leveled up on any player’s first turn of the game.
307.3f A Leveled Up Pokémon may not be leveled up.
307.3g A Leveled Up Pokémon is considered to be a single card that has all the attacks, Poké-Powers, Poké-Bodies,
and Pokémon Items of both the Level Up card and the card it leveled up from. HP, Pokémon Type, Weakness,
Resistance, and Retreat Cost are replaced by the corresponding properties from the Level Up card. Any elements
from previous evolution stages are not accessible.
307.3h If an effect removes the highest Stage Evolution card from a leveled up Pokémon, both the Level Up card and the
highest Stage Evolution card are removed, and both cards go to wherever the effect specifies the Evolution card
should go.
307.3i A Leveled Up Pokémon is considered to be the same evolution stage as the card it leveled up from. This is an
exception to 307.1.
It's not 'Evolving', but it follows the same rule as evolution: The pokemon has to have already been in play at start of your turn.
