This article is historical and may be significantly outdated.
1998: It's been ten years since Pokémon was released in the United States. For the first three years, it was a fad on everyone's tongue. Children felt that they needed to have everything and anything Pokémon-related that they could get their hands on. Going to a store was a nightmare for some parents. They often scolded their kids and had to keep them away from the toys. Trading cards were "playground money" at the time. Everyone had to have the rare cards, especially the holographic Charizard from the Base Set. Booster packs sometimes sold for more than six bucks a pack (that's 11 cards). The television anime was also all the craze. Kids couldn't wait to get home to watch their favorite show. Every day at 4:00 PM on Kids' WB! is when it would come on. "Gotta catch 'em all" became a famous quote.
The first movie was a hit for anyone caught. Theaters sold out, and phone lines jammed for radio stations giving away free tickets. Kids begged their parents to see it not once, not twice, but several times! Their parents surely became sick of it, hearing (to them, at least) all the monotonous (both definitions) battling and esoteric jargon. But, as best put by Dream Street's song on the Pokémon 2000 album, "They never can understand Pokémon." Of course, the second movie did well in theaters and was claimed to be better than the first.
There were also two video games that sold millions: Red and Blue. Soon after, a third version dubbed the "Special Pikachu Edition" was released, or as most knew it, Pokémon Yellow. You almost couldn't see a Game Boy without one of these games in it! It was ubiquitous! How could such a simple game be so popular? Children loved the monsters and the collection aspect, and the older teens loved the strategy required in it. And with Pokémon Stadium, you could battle in 3D and play the GB games on the big screen!
The world didn't know what mass marketing was before Pokémon came along. Billions of dollars of merchandise flew off store shelves, and plush Pikachus and Game Boys topped Christmas lists. It was all about who had the best Pokémon present, who had the rare cards, and who had a Level 100 Mewtwo. Rumors spread and became well known. People tried all kinds of fake tricks, bought GameSharks, and hacked illicitly. And knowing about Mew was no better.
However, the next generation came about in 2000, and became an instant hit among mostly the same people. Those who loved it wanted more from the series, and Game Freak didn't let them down. They brought on another 100 monsters with Gold and Silver (that's 251), which some consider to be the best of the series for its time. The Game Boy Color was somewhat new, having been released two years prior. Regardless of the new system, all of the main games could be connected with a Game Link Cable or a Transfer Pak. Anything from the first generation could be traded across the color/metal gap. By then, Pokémon 3 and Pokémon 4Ever were out and started to fade from theaters.
But the formula remained similar, more television seasons aired, and more cards flew out of the factories. This was the climax of the craze...at least for then! 2001 was reckoned as the drop-off point of the whole Pokémon phenomenon. After Crystal version, fans started to leave. People began to say "adios" and move on to something new. Some left to Yu-Gi-Oh! and others moved to the PlayStation 2. They were growing up and felt that Pokémon was for kids.
2003 marked the next generation, with Ruby and Sapphire, bringing the total to 386. But (as some saw it) it was already too late. Many people left, and some felt the pair of jewels were of poor quality. But that didn't stop really eager fans from getting their hands on the new games. They still sold like hotcakes and flew from store shelves. But this did mark a new beginning, as connection with past games was not possible and only 200 could be gotten in-game. Pokémon, USA took over the card game from Wizards of the Coast and started producing them exclusively. But card and toy sales were on the decline...rapidly. By the time FireRed and LeafGreen came out (along with the wireless adaptors), fans were less obvious. You wouldn't hear "Pokémon" as much as in years past. Nintendo had to rethink their marketing stratetegies. The Game Boy Advance was slowly dying at the advent of the new DS. At least the new Red/Green remakes allowed you to complete the Pokédex. More movies came out, and the phrase "Gotta catch 'em all" was officially dropped.
Of course, Nintendo and Pokémon were in need of a revival, which started with Emerald version. It came about with such a risky plan. The plan would either bring it back lots of faithful fans or kill the series. The risk started in late 2006. Advertising of a new generation started. The DS Lite was a major product, selling thousands, the Wii was hot, and Nintendo was heading toward the top, already ahead of Sony, and just behind Microsoft. The show had switched to Cartoon Network and the cards were revised. Merchandise was created. 2007 was the year of the Pokémon...again.
Forums exploded with prerelease info, leaks of images, fake Pokémon, rumors, card info, statistics, airdates, and more for Diamond and Pearl! It all started with the early releases of Munchlax, Lucario, Manaphy, Mime Jr., Buizel, Chatot, and Mantyke to the public. And Lucario and the Mystery of Mew's viewer count marked that fans were coming back. Millions of fans couldn't wait until that fateful day: April 22, 2007. Nearly a million people went to the release party in New York City to celebrate the new games and pick up their reserved copy. The line to get in was huge, as was the line to buy the game.
Many old fans returned to the series to see themselves talking to Professor Rowan, just as they talked to Oak a decade ago. Only this time, the GTS and full Wi-Fi made the game almost a certain hit. Millions more had the game and trained, just as always. Only, this time, it was all about having the ultimate Arceus, which still hasn't been released to the public. DS systems were everywhere, cards were selling like crazy again, and the net was flooded. Pokémon was back! And this time, there's 493 and it's possible to catch them all! (According to sources, the phrase may be back again.)
Now, it's 2008 and many people are waiting for the next movie, The Rise of Darkrai. According to people that have seen the Japanese one, it may actually be the best Pokémon movie so far. The anime has changed significantly, as well. Bulbapedia says that the show has improved and is as good as the first season in the sense that it has become rather unpredictable. Main characters are trading Pokémon, the "episode formula" has been broken many times, and people from older seasons are coming back. (A recent episode includes Gary again!)
Only time will tell the future of Pokémon.