The Detective Pikachu Pokemon roster was decided by a mix of nostalgia and one game in particular, according to the director

The Detective Pikachu movie is bringing the world of Pokemon to life but, try as it might, there was just no way they could include all 807 ‘mon into the hustle and bustle of the franchise’s first live-action movie. So, how do you go about cutting them down? Well, the Detective Pikachu director has opened up on the process – and has also confirmed the number of Pokemon that are in the movie.

In an interview with ET, Rob Letterman explains that one Pokemon game held precedence when it came to whittling down the hundreds-strong roster into a smaller group, and it’s almost definitely not the one you’re probably thinking of.

According to the director, “The Detective Pikachu game had a certain grouping that was already baked in.” If you haven’t played the 3DS title, then that’s basically shorthand for Pikachu (duh) and a supporting cast of the likes of Skorupi, Buneary, and Noviern, who all have roles to play in the plot.

Elsewhere, our good pal nostalgia was brought into the mix and the reasoning is, well, pretty simple: “We went to the first-generation Pokémon, the fan favorites, because we wanted to put in the Pokémon that people in their twenties and thirties would remember, the ones they grew up on, the nostalgia of that,” outlines Letterman. 

In the trailers, we’ve already seen the likes of Charizard, Mewtwo, and Psyduck, who all had major parts to play in the anime and formative years of the Pokemon games, so that checks out.

Just don’t go expecting the original 151 to all rock up, though. Letterman reveals the number of Pokemon in the movie is “Around 54. But I don't know the exact, exact number. And there's over 800 Pokémon in the Pokédex, but we ran out of money around 54!”

Wanna catch ‘em all? Here’s a list of every Pokemon in Detective Pikachu.