Pokémon Legends Z-A is getting a DLC expansion post launch, dubbed Mega Dimension - and it features not one but two Mega Raichu evolutions.

There's very little to go on from the trailer - a seconds-long sizzle showing Hoopa opening a portal, followed by the two Raichu Megas, Mega Raichu X and Mega Raichu Y, darting about looking cool - but there is one interesting twist. Raichu was, a very long time ago in the original, first-generation games of Pokémon Red, Blue and Green, set to have a standard evolution of its own.

That evolution was known as Gorochu - and Pokémon fans have been desperate to see it in a real game for years.

The news, revealed via the latest Nintendo Direct today, came just after the reveal of three other Mega evolutions for the three gen 6 starter Pokémon: Mega Chesnaut, Mega Delphox, and Mega Greninja. The Mega Stones required for those an be found "as rewards for being promoted up the ranks in online Ranked Battles," according to the official blurb - you can read up on those and the rest of the new Megas announced for the game in our full list of new Pokémon Legends Z-A Mega Evolutions.

Likewise, before we get into the weeds on Gorochu, here's all the official blurb we have on the Pokémon Legends Z-A - Mega Dimension DLC:

The new downloadable content will allow Trainers to continue their story with Team MZ after completing the main story of Pokémon Legends: Z-A.

The Mischief Pokémon, Hoopa, seems to hold the key to Mega Dimension's story. This Mythical Pokémon can warp space using the rings on its horns and around its body. These loops are stretchable and can form holes inside them leading to far-off places. Spatial distortions have also appeared in Lumiose, giving fans even more to discover throughout the city.

Two newly discovered Mega-Evolved Pokémon, Mega Raichu X and Mega Raichu Y, have been revealed. Mega Raichu X floats using electromagnetism, concentrating electricity into its fists to land devastating blows. Mega Raichu Y strikes foes swiftly with the amplified electric power coursing through its body. Mega Raichu X and Mega Raichu Y each require a different Mega Stone to Mega Evolve, and both can be encountered in Pokémon Legends: Z-A - Mega Dimension.

Right, so Gorochu.

Its existence was first confirmed in a 2018 interview, featuring an extremely rare appearance from Atsuko Nishida, the original designer of the Pikachu evolution line. Nishida, who is extremely publicity-averse (in this video interview she spent the whole thing hiding behind a Pikachu plush), spoke alongside fellow developer Koji Nishino, the man responsible for hiding Pikachu behind super-low spawn rates in Viridian Forest because he liked the design so much, and legendary Pokémon co-creator and lead creature designer Ken Sugimori. And she confirmed Gorochu somewhat nonchalantly.

Here's an extract, from the original interview on Pokémon.com (via Pokémon historian Dr Lava), which was conducted by Japanese newspaper Yomiuri:

Yomiuri: "Did you receive any orders when creating Pikachu?"

Nishida: "There were no specifications other than gameplay ones, such as it had to be Electric-type and that it would evolve twice. I designed Pikachu and Raichu based on that."

Sugimori: "Weren't you told to make it an Electric-type Pokémon and to make it cute?"

Nishida: "No, I wasn't. I was told to make its final form look strong. That's right, there was an evolved form after Raichu at the time. Its name was Gorochu. It had fangs and horns and looked like a god of thunder."

Yomiuri: "Why was this Gorochu rejected?"

Nishino: "That's because, in the game specifications, Pikachu ended up being the kind of Pokémon that evolves only once."

Sugimori: "There was nothing wrong with its appearance--it simply had to do with the balance within the game."

Nishino: "There was also a problem in terms of the size of the game data. We had to save space by taking Pokémon originally designed to evolve twice and making them evolve only once. Pikachu was not one of the first three Pokémon, so it was an easy target for this kind of reduction."

Roughly a year later, we got one, tantalising glimpse at Gorochu: a "back sprite" - the view of the Pokémon from the back, as seen during battles in gen 1 Pokémon games - and nothing else. This came via a beta leak uncovered by another archeological Pokémon fan group, known as Helix Chamber. (Worthing noting here: the person who leaked it to Helix Chamber ultimately turned out to be a hacker - unbeknownst to them - which also led to the verification of the leak itself. Court documents from a lawsuit against the hacker then confirmed the legitimacy of the files.)

Pokémon fans, or at least one fervent section of them, have been desperate to see Gorochu ever since. A late-2018 interview with Gamespot from another long-serving senior developer Junichi Masida, after that Nishida interview, dashed those hopes. "You're probably not going to see it," he said. "None of the Pokemon that we worked on, got to a point, and then discarded them have actually ever re-appeared yet, so I would say the chances are low".

Which brings us back to today and, no, Mega Raichu X and Mega Raichu Y are not Gorochu. In fact, their existence makes the likelihood of anything ever known as Gorochu - a name, like Pikachu and Raichu, that comes from combining the Japanese onomatopoeia terms of thunder and a mouse's squeak - even less likely. With Pichu, Pikachu and Raichu forming a three-stage evolution, and now Mega Evolutions for that line confirmed too - and a regional varient in Alolan Raichu - this is almost certainly it.

But both Mega Raichus do have fangs. And they have horns, of different kinds each. And leaping into the air, flashing golden yellow and lingering there against the backdrop of a whailing electric guitar, you could say they have a bit of "god of thunder" about them, too. If nothing else, this feels like a design that's taken genuine inspiration, or some form of lineage, from that original concept for Raichu's evolution. This is probably as close to the long lost Gorochu as we're ever going to get.