Meh Gallade is better as a status plateau tank or even a Choice Band user than a Scarf user, Medicham outclasses it in every way shape and form if you want a Psychic/Fighting Scarf abuser (PURE POWER FTW) . You need more bulk on its Evs btw.
Try
Gallade@Leftovers / Choice Band / Expert Belt / Life Orb
236hp/252atk/20speed
Adamant Nature
- Close Combat
- Psycho Cut
- Night Slash
- Hypnosis / Thunder Wave / Will-O-Wisp / Stone Edge / Leaf Blade
Close Combat is obviously there for STAB, Psycho Cut so you dont get walled and lol'd at by Weezing and Heracross. Night Slash for Cresselia etc and Dusknoir. Last move is up to you either a status or Stone Edge for Gyarados and Salamence etc. Leaf Blade should only be used if you have some sort of weird Swampert or Bulky water problem.
EV spread gives it 201 speed, not like it really needs to outspeed anything important, if your really scared of faster foes thats why Thunderwave is there (Dont say Gengar, if you invest speed evs and give it a scarf it takes away its Bulkyness therefore its tanking ability,with Scarf on Gallade, Gengar will switch in on Close Combat regardless, forcing you to switch anyway) its actually bulky and can take more hits than youd think with the Hp investment. Also it has fantastic special defense, which it should be given credit for.
Alternately you can go double status and replace Night Slash.
EVS give it the following stats : - 336 HP / 383 ATT / 166 Def / 201 Speed /266 Special defense . The perfect tank in my eyes and very hard to counter if your good at predicting switches. Which is what you should be doing with it. Send it on something that dies to it and 9 times out of 10 if your opponent is a remotely good player they will switch, this is when you either sleep/ Paralyze/Burn their Gallade counter on the switch in and take it from there, either switch if you cant beat it, or lol at a paralyzed Gengar, burned Metagross , or an asleep whatever etc. and Psycho cut/Close Combat <insert move here> the living daylights out of it.
EDIT: TO PROVE HOW BULKY IT IS
Max sp.att Timid Gengars Shadow Ball does
Defender HP: 336 (This is with 236 HP EVS and 0 sp.def evs)
Damage: 236 - 278
Damage: 70.24% - 82.74% (lol)
fails to even OHKO it.......
You basically beat Gengar if you paralyze it on the switch in even if it has a Focus Sash.
You send in Gallade
Opponent switches in Gengar
Gallade uses thunderwave
Gallade uses Psycho Cut, Gangar hangs on with its Sash, so what ?
Gengar uses Shadow Ball
Gallade: lol
Gengar uses Psycho Cut again.
Gengar: Ouch