Blooper: Before the post-game superboss battle with Steven in Emerald, he says, "We battled alongside each other at the SOOTOPOLIS SPACE CENTER." The Space Center is actually located in Mossdeep City.
There is an ability called Cacophony hidden in the games' code. Its description is identical to Soundproof, but it has no effect programmed and no Pokémon have it, and it was removed in Pokémon Diamond and Pearl.
Secret Base Dolls for Regirock, Regice, and Registeel exist in the codes, but there is no way to get them without a cheat device, as they were only accessed from a Japan-only promotional e-Reader card.
There are six hidden tracks in Ruby and Sapphire, five of them GBA remakes of Generation II tracksnote the Pokémon Communications Center theme, the Route 38 theme, the Team Rocket Radio Tower Takeover music, the Raikou/Entei/Suicune battle theme from Crystal, and the redone Viridian/Pewter/Saffron City music and the last one an alternate arrangement/possible demo of the Littleroot Town music. Emerald also contains the entire soundtrack from FireRed and LeafGreen, though it does use a few tracks from the latter.
Item sprites for Red and Blue Orbs exist in Emerald (a carryover from FireRed and LeafGreen even though they cannot be obtained there normally) but remain unused as the player never gets to seize the orbs themselves.
Generation III was the first generation to introduce ribbons, which are attached to Pokémon as an award for accomplishing something. Alongside ribbons that are awarded to Pokémon for defeating the Pokémon League, clearing Contests or clearing the battle tower, there are a whopping 64 ribbons that are not obtainable within the GBA games. Only 2 of these are available through Pokémon Colosseum and Pokémon XD (the National Ribbon, which are awarded to purified Shadow Pokémon, and the Earth Ribbon, which are awarded to Pokémon that clear Mt. Battle). The rest refer to events (such as battling competitions) that were apparently planned, but ended up not happening. The most mysterious are the tower ribbons, which are awarded for clearing places known as "Darkness Tower", "Red Tower", "Blackiron Tower" and "Final Tower". Nothing like that is even hinted at anywhere else in the Pokémon series.
Killer App: Ruby and Sapphire are the best selling titles to ever grace the Game Boy Advance, with more than 16 million units sold between them. Emerald is the third most successful with more than 6 million units sold, only beaten by the above titles and FireRed and LeafGreen.
Meaningful Release Date: Emerald was released on May 1, 2005 in the US; the emerald is the birthstone of May. Plus, "May" is also the name of the female rival in these games.
Early on after the release of Ruby and Sapphire worldwide, rumors about being able to find wild Celebi on Route 117 cropped up, with an unbelievably low encounter rate, like one in 20 million. Nothing in the game's code suggests that Celebi can be found there.
Another one involves a white rock that can be found in Mossdeep city. Apparently there is a tradition to attach slips of paper to it for good luck. This naturally spawned rumors of the rock actually being Jirachi that'll awaken when a certain number of rockets have been launched. None of these rumors are true and the white rock is just a red herring unconnected to Jirachi.
And, of course, related to the rockets was one of Gen 3's most (in)famous examples: that certain launch counts would let you go into outer space to catch Deoxys and/or Jirachi. 50 and 99 were two of the most widely-cited numbers.
It was stated in a Nintendo Power interview that Diamond and Pearl Pokémon Shellos and Gastrodon were originally designed for Ruby and Sapphire, but ultimately they were not implemented due to time constraints.
Ruby and Sapphire were intended to be a Soft Reboot of the franchise, hence the red and blue cartridges. This is why Wumple and Tallow are similar to the Caterpie and Pidgey lines.
The games' name couldn't be agreed upon for four months until the team thought of continuing the theme from Crystal, specifically by using corundums, a type of crystal classified into rubies and sapphires. However, The Pokémon Company objected because they didn't want the games to be named after crystals. They had to relent due to the game being far late into development.
Trivia for Omega Ruby and Alpha Sapphire:
Dummied Out: As you're not supposed to encounter most Pokémon within the game's demo, only a select few are programmed into the game. The rest are replaced with placeholder data a la Missingno from Pokémon Red and Blue. What's unique about this is the fact that said placeholder data happens to be an actual canon Pokémon but with a cry different than normal. To be specific, it's a ?-form Unown that has the cry of a Bulbasaur. [1]
Fandom Nod: The original games were rife with rumors that you could go to the moon on a spaceship from Mossdeep to battle Jirachi or Deoxys. Come ORAS, and Deoxys is indeed fought by riding Mega Rayquaza into space.
Official materials state that none of the Mega Stones introduced in Omega Ruby and Alpha Sapphire can be traded over to Pokémon X and Y. In actuality, Latiasite and Latiosite can be traded and will even function since their data was left in X and Y.
The official site had advertised Megas using moves they can't legally learn, such as Diancie with Power Gem and Blaziken with Ice Punch. Once the games were out and people were able to confirm those moves were unobtainable, an official statement with an apology was released and the misleading images were removed from the site. Diancie would eventually be able learn Power Gem through legal means in Generation VII.
Trolling Creator: Flygon is one of the biggest Ensemble Darkhorses from Gen III, and most people were expecting it to get a Mega. Not only does it not get one, the game's most notable Flygon user, Aarune, gives you Garchomp's Mega Stone instead.
In a Nintendo Dream interview in April 2015, Ken Sugimori revealed that Game Freak had attempted to include a Mega Evolution for Flygon in Pokémon X and Y and then Omega Ruby and Alpha Sapphire. It fell through because they couldn't come up with a design they were satisfied with.
The ability Levitate and a higher Attack boost were considered for Mega Metagross, but Tough Claws and the large boost to Speed won out due to give it more options in battle.
. Shifting from the Game Boy to the Game Boy Advance required a lot of adjustment for Game Freak due to the significant upgrades in hardware. There was also uncertainty about the future of the franchise, as Pokémon was seen as a fad and the initial Pokémania wave was waning after Pokémon Gold and Silver released.
