Gliscor is better off as specially defensive nowadays. Even though its Special Defense is normally bad, this makes it better against things like Therian Tornadus and non-Hex Gengar. Gliscor is also seen as a stall breaker, meaning it has no room to fit in Stealth Rock Otherwise, Therian Landorus is the better alternative, as it has Intimidate to weaken physical attackers, while having the freedom to run Stealth Rock:
Gliscor:
-Swords Dance
-Earthquake
-Knock Off/Facade
-Roost
Nature: Careful
EVs: 244 HP/8 Def/200 SDef/56 Spe
Item: Toxic Orb
Ability: Poison Heal
or
-Earthquake/Knock Off
-Taunt
-Toxic
-Roost
Nature: Careful
EVs: 244 HP/8 Def/200 SDef/56 Spe
Item: Toxic Orb
Ability: Poison Heal
Therian Landorus:
-Stealth Rock
-Earthquake
-Stone Edge/Rock Slide/Knock Off
-U-turn
Nature: Impish
EVs: 252 HP/240 Def/8 SDef/8 Spe
Item: Leftovers/Rocky Helmet
or
-Stealth Rock
-Earthquake
-Stone Edge/Knock Off
-U-turn/Explosion
Nature: Adamant/Jolly
EVs: 72 HP/252 Atk/184 Spe
Item: Soft Sand/Earth Plate/Focus Sash
Bisharp makes an excellent teammate to Mega Gallade because both beat on each other's counters. Bisharp handles Ghost, Fairy, and Psychic Pokemon, while Gallade handles Fighting Pokemon:
-Sucker Punch
-Knock Off
-Iron Head
-Swords Dance/Pursuit
Nature: Jolly/Adamant
EVs: 4 HP/252 Atk/252 Spe or 252 Atk/52 SDef/204 Spe
Item: Life Orb/Black Glasses/Dread Plate/Lum Berry
Ability: Defiant
or
-Sucker Punch
-Knock Off
-Iron Head
-Pursuit
Nature: Adamant
EVs: 192 HP/220 Atk/96 Spe
Item: Assault Vest
Ability: Defiant