You get it from a man in Castelia City.
Go into Shady Alley in Castelia City. Talk to the man behind the dumpster and he gives it to you.
You do not get any HMs in Castelia City.
By size the largest city is Castelia city. By population it is Nimbasa
Go to Castelia city and enter the third street from the entrance. when you enter there will be dumpsters on the left side, with a lamppost. Go to it and you will see a man behind the dumpsters who will give you flash.
You get it from a man in Castelia City.
A man gives you the TM in an alley in Castelia City.
It's called Flash, and you get it by a guy in a backstreet in Castelia City.
It is in the Castelia City's Alleyway and someone would come out and give it to you.
In castelia city on narrow street talk to the dude behind the dump
In Castelia City when you go down the third ally starting from when you first enter the city
Go into Shady Alley in Castelia City. Talk to the man behind the dumpster and he gives it to you.
u go to Castelia City and go in 1 of the alleys. he'll just pop out of nowhere then he'll give u TM Flash
In Castelia City. Second alley from the left, there will be a man talk to you after you pass up the dumpsters and give it to you.
You do not get any HMs in Castelia City.
1. Flash is a TM 2. You can find TM Flash in Castelia city 3rd gap from the right go near the dumpster and a guy with sunglasses will appear he will give it to you.
In the Generation V games (Black, White, et cetera) Flash is not an HM. To find it (as TM70) go to Castelia City. down one of the streets (the narrow one with dumpsters) you will find a man behind a dumpster. talk to him to receive TM70 Flash.