A player can reveal and play an Evolution card at any time. Some Evolutions are temporary, allowing a one-time bonus, while others are Permanent, such as Gigazaur’s “Tail Sweep”, which allows him to change one die to a 1 or 2 each turn. Each Evolution card also identifies whether a monster is a Mutant, Invader, or Robot, and while not relevant for Power Up!, this species identification could come into play in future expansions.
The rules for King of Tokyo: Power Up! contain a few variants: Players start with a random Evolution in play, or draw two cards and choose the one they want, or draft a set of Evolutions prior to the start of play. However you play, the goal of the game remains the same: Score 20 points or be the last monster standing amid the rubble of what was once Tokyo.