Invasion! Mega Rayquaza (Tretta)

Invasion! Mega Rayquaza continues to feature elements from Pokémon Omega Ruby and Alpha Sapphire, with the inclusion of both a Rayquaza capable of Mega Evolution and the Pokémon Tretta debut of Deoxys, two plot-centric Pokémon in the post-game Delta Episode.

Rayquaza is featured as the set's Legend-class Tretta, and is the first Legend-class Pokémon that can Mega Evolve. The set includes another eight Pokémon that can Mega Evolve. These include: Metagross, Salamence, Gallade, Gyarados, Lucario, Heracross, plus the Eon duo Latias and Latios. Latias is included as the set's Secret Tretta. All regular Tretta are colored sky blue in this set.

Invasion! Mega Rayquaza also marked the start of a cross promotion between Pokémon Tretta and the Pokémon anime, with the inclusion of a Pikachu based on the one belonging to Ash Ketchum in this set, and a promotional Pancham based on Serena's released shortly afterwards. Both of these Pokémon feature unique character models when used in-game, with Pikachu wearing Ash's hat and Pancham wearing Serena's sunglasses.

Search Mode includes locations from Gogo Field, which features a dual winter and spring theme, a reference to the proximity of this set's release relative to the previous one. Ruins, after being absent in the last set, returns, with the similarly long-standing Field location absent for the first time, now making Forest the only location to appear in every set.

Challenge Battle was also slightly expanded from this set. After the conclusion of Battle Mode, players with Tretta Reports could obtain the Legendary Pokémon Xerneas or Yveltal as Extra Attackers via Extra Chance (Japanese: エクストラチャンス). Extra Chance presents players with a roulette consisting of 10 spaces, which has a starting configuration of 9 × spaces and 1 O space. The player can stop the roulette by pressing one of the two main console buttons once it starts spinning. If a player lands on a O space, they will obtain an Extra Attacker. Players can replace × spaces with O spaces on the roulette by winning battles in Challenge Battle, increasing their chances of obtaining an Extra Attacker.