Gallade can learn some moves by egg-breeding such as Ally Switch, Confuse Ray, Destiny Bond, Disable, Encore, Gurdge, Mean Look, Memento, Misty Terrain, Shadow Sneak, Skill Swap and Synchronoise.
Gallade's role is a Physical Sweeper and if you see, almost all don't get in the moveset beeing all status-moves, 1 physical (Shadow Sneak) and 1 special (Synchronoise).
Gallade should have in the set some moves such as Swords Dance, Close Combat, Leaf Blade, Shadow Sneak, Earthquake, Night Slash, Bulk Up, Elemental Punches and others, so what I suggest from egg-moves is only get Shadow Sneak.
Since Gallade is a physical sweeper, Synchronoise has a great base-power but it's a special-move. I recommend you having a Swords Dance with a priority move such as Shadow Sneak, having a STAB such as Close Combat and Earthquake or another move with great power.
Hope this helps.