The Demo Version features a unique scenario that begins in Mossdeep City, where Steven requests the player's (locked as Brendan with the name "Orlando") assistance at the Mossdeep Space Center, where they are intercepted by a male and female Team Magma or Team Aqua Grunt (randomly determined). The player is given a choice between a level 35 Grovyle, Combusken, and Marshtomp to help Steven fight them off.
After the battle, a professor who works at the Space Center will inform the player and Steven that the evil team they just fought is seeking out a Pokémon with a recently discovered Mega Evolution. After Steven gets the coordinates of the unnamed island the Pokémon is located, the player is allowed to explore Mossdeep City before returning to Steven to begin their pursuit.
After riding Latios or Latias to an unnamed island, Steven will tell the player to go forward, where they'll encounter wild Pokémon, several grunts from each team, and May, who came to investigate, but was overpowered by the enemy. May will heal the player's team. At this point, the player's Pokémon will have reached it's final evolutionary form.
At the back end of the island cave, the player will find Aqua Admin Matt and Magma Admin Tabitha, who call a truce to take the player down. However, Steven intervenes, giving the player three gifts to shift the battle in their favor. First, he overwrites the player's Pokémon's Status move with its respective Hyper Beam variant (Frenzy Plant, Blast Burn, or Hydro Cannon). Next, he gives the player a Mega Bracelet, and gives the player's Pokémon its respective Mega Stone to hold. Thanks to these gifts, the player and Steven defeat the two admins easily.
After clearing Team Magma and Team Aqua off the island, Steven leads the player to a deeper part of the cave, where a single patch of tall grass houses the Pokémon sought after by the two villainous teams. Steven gives the player five Poké Balls to capture the Pokémon. After a successful capture, the two trainers return to Mossdeep City, the adventure ends, and progress made is saved.
The player can continue to play the demo afterwards, visiting various other islands, and gaining access to the other two starter Pokémon at level 40. After each journey, any experience gained is reset. As the player completes more adventures, more NPCs, including Gym Leaders and new characters such as Lisia and Aarune, will appear in the city. The player can talk to Steven to bring over the new Mega Pokémon, as well as item bundles they receive from clearing adventures, to their full Omega Ruby or Alpha Sapphire game via Pokémon Link. The player will stop receiving item gifts after the tenth adventure.