From 1996 to 2013, the mainline Pokemon game formula remained largely the same: players begin an adventure as a new Pokemon trainer, choose their starter Pokemon, set out to fill out their Pokedex while competing in the Pokemon league, and take down a villainous organization in the process. For the most part, everything was cut and dry for the better part of the series' lifespan, aside from additions like new Pokemon, new types of battles, and changes in mechanics.

However, it's safe to say that all of that changed with the introduction of the Pokemon X and Y games in October of 2013, which marked the series' first ever simultaneous worldwide release. These titles were already monumental for the franchise, as they were the first fully 3D Pokemon games. Little did fans know, they were about to receive much more than the addition of the brand new Fairy type. They were going to see the series' first ever game-changing mechanic: Mega Evolution.

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Initially, many fans considered the Mega Evolution mechanic to be a gimmick that would never stick. However, years later, fans are begging for it to make a return to mainline Pokemon titles. Since its debut, fans have been introduced to new gimmicks like Z-Moves, Dynamaxing, and Gigantamaxing, with Mega Evolution since being phased out of the series, but not entirely. Now, it looks like Pokemon games can't decide what to do with Mega Evolution, resulting in a strange relationship with the fan-favorite mechanic.

In Pokemon X and Y, Game Freak introduced fans to Mega Evolution, a form of temporary evolution that certain Pokemon can achieve resulting in a change in appearance, increased stats, possible type changes, and more thanks to a strong relationship with their trainer. While fans were unsure of the mechanic at first, many began to vouch for it as the spice the series needed to keep it fresh, shaking up the game's typical formula, as well as brining new life to the competitive Pokemon meta.

Mega Evolution quickly became synonymous with the 6th generation of Pokemon, even making its way into the next year's mainline installments, Pokemon Omega Ruby and Alpha Sapphire, remakes of the 3rd generation games. After its inclusion in Omega Ruby and Alpha Sapphire along with brand new Mega Pokemon, fans seemed certain that the new mechanic would be a mainstay in the franchise, but were also curious as to how it keep itself fresh. But at the same time, Mega Evolution had made its way to many of Pokemon's spin-off titles as well.

The mechanic eventually made its way into many Pokemon spin-off games, which became increasingly abundant with free-to-play titles on both the Nintendo 3DS and mobile devices.

The first of these was the Pokemon Trozei-like mobile game Pokemon Shuffle, which incorporated Mega Evolution as a way to make more matches in the game. Pokemon Rumble World quickly followed suit, being a free-to-play installment of the Pokemon Rumble series on the 3DS, making Mega Evolutions work much like they do in the mainline games. In addition to titles like Pokemon Picross and Pokemon Duel, the mechanic also came to Pokken Tournament and Pokemon Super Mystery Dungeon, but after that is where the series' relationships with Mega Evolution really gets confusing.

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While the temporary evolution gimmick had become normalized in the Pokemon franchise as a whole, making its way to the TCG and anime as well, fans weren't quite sure what to expect with the 7th generation of Pokemon games. What made things even more rocky was Pokemon Sun and Moon's brand new gimmick mechanic, in the form of Z-Moves: ultra-powerful attacks that any Pokemon could perform when holding a Z-Crystal of the same type as any one of their moves. While these were much more inclusive than Mega Evolutions, many argued that they lacked a certain unique charm and ultimately came off as bland and unexciting.

It initially seemed like Z-Moves were replacing Mega Evolutions entirely, but just weeks away from the launch of Sun and Moon, fans received confirmation that they would be present in the games, but not explored any further. Pokemon game director Junichi Masuda has explained that the reasoning for this is due to Game Freak wanting to make each player feel like they can use their favorite Pokemon in a special way with Z-Moves. Ultimately, it seemed to many like this marked the phasing out of the gimmick mechanic, but things only got more strange from there.

While many weren't quite sure what to expect from the Pokemon series in 2018, it was announced that fans would be returning to Kanto once again for Pokemon Let's Go, Pikachu! and Let's Go, Eevee!. To this day, it is debated among fans as to whether these games can be considered mainline titles or spin-offs, mainly due to how much the conventions of the games changed to match the 2016 mobile hit Pokemon GO. Despite this, fans were excited to see Mega Evolution make a return, but were confused that it seemed less sidelined than in Sun and Moon, with it being more incorporated and not simply relegated to Let's Go's postgame.

Now, aside from Pokemon Let's Go, Pikachu! and Let's Go, Eevee!, which seem to be up for debate anyways, fans haven't seen a new instance of Mega Evolution in almost three years. It seems that Game Freak essentially put the nail in the Mega Evolution coffin with 2019's Pokemon Sword and Shield on the Nintendo Switch, which introduced even more new gimmick mechanics with Dynamaxing and Gigantamaxing, getting rid of both Z-Moves and Mega Evolutions entirely. Many fans consider this to be where the mechanic "died," but for whatever reason, The Pokemon Company seems intent on keeping it alive in Pokemon's spin-off games.

Despite being excluded from Sword and Shield, Mega Evolution remains alive and well: Mega Evolutions came to ongoing 2019 mobile game Pokemon Masters EX, appeared as a core mechanic in 2020's Pokemon Mystery Dungeon: Rescue Team DX on the Switch, and was only just added to Pokemon GO late last year. Even now, ongoing Pokemon mobile games continue to update with content related to Mega Evolutions. While it seems that the mechanic has been relegated to existing exclusively in spin-off titles, that's not to say fans haven't been hopeful that they'll see it return once again.

Now, much of the conversation around Mega Evolution revolves around the upcoming 4th generation remakes, Pokemon Brilliant Diamond and Shining Pearl. Fans have noticed that aside from the more chibi overworld art style, battles in the upcoming games look very similar to those in Pokemon Let's Go. With ILCA taking over development of Brilliant Diamond and Shining Pearl, many have noted that this could mark remakes as spin-offs, which would make Mega Evolution seemingly even more likely to appear. While nothing is for certain yet, it is clear that Pokemon has had quite an interesting relationship with one of its most beloved mechanics.

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