Now that the first season of the Pokémon animated series is on Netflix, thousands of milennials can relive the brief, magical time when they felt the uncontrollable need to catch 'em all.

Pokémon featured a surprisingly robust catalogue of original music, and eventually spawned an album that sold more than 500,000 copies in the United States alone. But more than 15 years later, one earworm in particular stands out: the "Pokérap," a song that played at the end of every episode, and managed to squeeze the names of all 150 Pokémon into a surprisingly coherent track.

What was it like to work on such a bizarre project? The Week dug deep to find the untold story behind the Pokérap. The song's contributors include R&B singer James "D-Train" Williams, who was responsible for the hook, and John Siegler, who was the music director at 4Kids Entertainment. (Unfortunately, the actual Pokérapper, Babi Floyd, passed away last year.) In a series of recent phone conversations, the team behind the Pokérap explain how a catchy song from a then-untested cartoon ended up changing their lives forever. Here's a (slightly edited) transcript.

Siegler: The producers of the show wanted a song that named all of the Pokémon in the show at the time — this was the first season of Pokémon.

D-Train: Here in New York City, most singers are known by word of mouth, and when they're looking for particular sounds, producers used to call artists' services. So John Siegler, who used to do the Pokémon stuff […] needed someone to do the Pokérap. They called in myself and Babi Floyd.

Siegler: John Loeffler and I were songwriting partners. We wrote that song together. He and I figured out the singing section. "I want to be the best / there ever was / to beat all the rest / yeah, that's my cause." We wrote that melody, and the lyrics, and I executed the whole track as usual.

D-Train: Each week, they would build five characters, and then they'd add another five characters the next week, until — at the end of the season — you were up to 150.

Siegler: It was really the only practical way to get all of the names in. There are, what, 150? The song goes on and on and on, but we wanted it to have some kind of musical identity too, for people to sing along — so we'd sing a little bit, then have 12 or 15 of them. I had to go through the list and come through at least a vague rhyme scheme of all the Pokémon, so that if there were eight of them, at least the fourth and eighth would rhyme when we were listing them all out.

D-Train: I went with Babi Floyd. I would sing "I want to be the best," and Babi would come in and do all the raps for the Pokémon.

Siegler: Babi was unbelievable — God bless him — that man was unbelievable. I worked with Babi all the time. […] He was such a versatile, wacky kind of guy. He could sing, but he could also do total craziness.

D-Train: The theme ostensibly got longer, and they had to make edits where I was singing, so it would get the same amount of time.

Siegler: There was one Pokémon that got removed from the list, so Norman [Grossfeld] called me and said, "You gotta take this one out." But what we did was, at one point in the song, there's a group that yells "Pokémon!" instead of listing all the Pokémon. It didn't pass Standards and Practices; I think it was a copyright issue.

D-Train: My singing part was done once, but Babi Floyd had to go in every week, or every month, because they would add characters until they got up to 150.

Siegler: The other part of it is at the time when the show was on the air five days a week, the producers wanted to have a song they would put on in the last 60 seconds of the show. Obviously you couldn't hear all of them in 60 seconds, so we whacked it up into five sections so you could do it five days a week.

D-Train: What that did for me was open up the door to Japan, because I had done an international commercial in Japan with Benny Thomas. When I go over there to do live shows and sing it, everyone there knows it. So Pokémon opened up a whole world over there.

Siegler: If I remember correctly, [Babi and D-Train] actually went out and did it live a couple of times. If I remember, there was a street fair on 10th Avenue, and Pokémon must have had a booth or something. I went down with my younger son, who was the perfect age for Pokémon at the time, and we missed them doing it. I was sad because I missed them doing it, and my son was devastated.

D-Train: I haven't been back there to do anything for Pokémon, or for 4Kids Entertainment. It wound up being a bit of a bittersweet relationship. 4Kids Entertainment only paid us per season, and they didn't pay us residuals. So 4Kids gave us a buyout, one for six months, and then another for the next six months, which continued for two years, and after it went into syndication there were no royalties. As a result, most of the people who worked on Pokémon sued, with the exception of Babi Floyd and myself. It's a bittersweet pill to swallow, because I'm glad my children got to know that their dad did the Pokérap. But on the same token, you didn't make the same money that 4Kids Entertainment did, and they didn't seem to care.

Siegler: Were they treated fairly? Probably not. They did receive a secondary payment. My point is, everybody walked into the studio with their eyes open. They knew this was everything they were going to get. I was the guy who always made the call: "Hey, Babi, can you come in Thursday morning to do this gig?" And I'd tell them exactly what it was. "We're doing this thing, it's a complete buyout, you're going to make X, whatever it was, but that's it, we're not paying any residuals, or anything of any kind."

D-Train: We had signed contracts. John Loeffler pulled out after three seasons, and he said, "I'm washing my hands of it" before all the lawsuits started. Most of the people who work on Pokémon now are in Japan, I think.

Siegler: Nobody knew or imagined that it would become the success it did.

D-Train: We didn't know if Pokémon would take off or not. No one had ever seen a Pikachu, or Pokémon flying around in the air. Back then we had G.I. Joe, Transformers, and Barney. For kids, you're dealing with the imagination, so it can either catch on, or not catch on. [Thomas the Tank Engine] has caught on longer than any of those shows. There are things that last forever. Pokémon had a good run, and is still having a good run, because they'll keep doing it until they can't do it anymore.

Siegler: It's definitely one of my least favorites. It wasn't really a song; it was a way of saying 150-odd Pokémon names, so it wasn't particularly musically interesting to me. When we did the second one, I liked that one better — but not much because it was still the same deal. Compared to other things like The Pokémon Dance, or the Pokémon theme song, or the millions of other songs I wrote for Pokémon, that was definitely personally one of my least favorites. It was just a groove — and people yelling Pokémon names.