Hey. Heh, try asking the gym leader there about the legend, he'll be able to tell you all the extra details. Otherwise, there used to be twin towers there, and a legendary Pokemon sat at the top of both. A bad storm came through and lit one on fire, scaring the Pokemon that lived on it away.

Three Pokemon were trapped inside and died from the fire, so the one that lived in the other tower came and revived them before disappearing itself. Those three Pokemon made an appearance over the summer, from Team Rocket trying to catch them; they were called Raikou, Entei and Suicune.

[It's why he likes Ecruteak best; he actually stayed there for a good six months after his arrival, living in the basement of the burnt tower.]