its in blackthorn city right next to the pokemarket.
Move tutor only in Pokemon Platinum, HeartGold and SoulSilver.
Blackthorn city
croconaw evolves into feraligatr at level 30 and learn hydro cannon in Soulsilver and Heartgold once after reaching blackthorn city ( there is a house to the left of the Blackthorn city Pokemon center that has the move tutor, move deleter , ultimate move* tutor, and Ultimate dragon type move tutor*) and go to the Ultimate move tutor. *= there two ultimate move tutor, one for dragon type Pokemon only and one for fully evolved starter Pokemon like feraligatr and charizard.
In Blackthorn city. In one of the houses there.
As of Pokemon Omega Ruby and Pokemon Alpha Sapphire, you can take Staraptor to the Move Tutor in Battle Resort and teach it Sky Attack. For Generation IV, you can teach Staraptor Sky Attack from the Move Tutor in Pokemon HeartGold and SoulSilver.
you can find the move tutor on route 221
You have to teach it AncientPower through Move Tutor.
There is no tutor in d/p you must trade the Pokemon to platinum teach it from the shard move tutor in the survival area and then trade it back
the move tutor is in Fallabor city to the west. but first before he'll teach your Pokemon a move you need to give him a heart scale
The move tutor is on 2 island in the house next to the game place.
I don't think that it is a TM in Heartgold or Soulsilver Versions, but it can be taught to your Pokemon by a move tutor in a small house outside of the battle frontier.
there is no move tutor on blue/red/yellow. move tutor 1st appears in 2nd gen. games