The reveal of Meltan in Pokemon GO was a pretty big deal. It's unlike anything the Pokemon Co. had done before. It was so different from the norms that most players thought the reveal was an accident! Now we know it was all planned, and Pokemon Co. director Junichi Masuda has opened up about the whole process.
So actually yeah we tried really hard on this one - we didn't even tell company players, so even some of us were surprised when this came out as well, so only a few people know about the plan in advance so it really was a well-kept secret.
So normally I don't really post on Twitter things about new Pokémon or Pokémon that are featured or more often encountered in Pokémon Go on specific days - but on the day Meltan was released it was community day and there was Chikorita was the Pokémon of the day, and then 15 minutes before Meltan was set to be released I tweeted "oh, everyone hurry up and catch your Chikorita you've only got 15 minutes left!" [laughs] which was... out of the ordinary.
So in terms of who made the decision, so it was TCPI's PR team and Niantic, and also myself who got together and started talking about it, and really we were thinking about how we wanted people to first lay eyes on Meltan, and how to kind of make it appear like a cute Pokémon right from the start, so some people might look at it, if it were handled the wrong way, as "oh it's like a gross Pokémon", but they had it appear in Pokémon Go, kind of moving around, doing it's thing, and then you know, people would be like "Ooh, what's this now?!" And we thought that was the best way to kind of have Meltan first appear to the world.