>>46775886>Gen 1: Zapdos>Gen 2: Raikou>Gen 3: Groudon, then Fug in EmeraldThen I stopped keeping legendaries on my ingame teams. Sometimes I'll use a trio legendary in a ROM hack or something, though. In Ruby, my little kid brain was sufficiently wowed by the story encounter with a box legendary that it felt appropriate to keep him on my team.
In Emerald, I'm not gonna lie, I was just enthused by the idea of cheesing the Elite Four with a massively overpowered Pokemon. I checked back at Sky Pillar of my own volition rather than being told about it, though, so I saw it as a reward for rubbing my dumb kid brain cells together.