Not unless your Kirlia knows it upon evolving into Gallade. Your Welcome :)
psychc and fighting.
Gallade can learn night slash, but not by level up. To teach Gallade night slash the player most go to Pastoria city and go to the south part of the city then go into the house at the top right of the southern part of the city. There is a guy who can teach Gallade night slash for a heart scale and all other moves it learns before that. I hope that helped!
You have to learn it at the Platinum/HeartGold/SoulSilver Move Tutors.
Well, If you teach Gallade the right moves, yes. Teach Gallade the following moves: Majic Leaf{so you can defeat water type Pokemon}, Psychic {it's a good move}, Brick Break {so you can defeat the Dark type Pokemon that might get on your nerves, and any other move you believe you might need.
There are three types that are super effective against psychc pokemon. They are Dark, Ghost, and Bug. If you need any other information type in psychc types on Wiki
Kyogre(Water),Rayquaza(Dragon,Flying),Jirachi(Steel,Psychc),Deoxys(MOST RARE!)(Psychc)
fire
Ghost, bug, and dark
Golduck is the only one I know.
Out of the many many many moves Gallade can learn, Perish Song can not be taught to Gallade. My Gallade is Po. I tried before I answered. :(
Psychc moves
Dark, Ghost and Bug types