duh

/setblock ~ ~1 ~ mob_spawner 0 replace {SpawnCount:10,MaxNearbyEntities:50,SpawnRange:1,Delay:20,MinSpawnDelay:60,MaxSpawnDelay:120,RequiredPlayerRange:6,EntityId:Skeleton,SpawnData:{id:Skeleton,PersistenceRequired:0b,CanPickUpLoot:0b,Attributes:[{Name:"generic.knockbackResistance",Base:1f},{Name:"generic.movementSpeed",Base:10f}],Equipment:[{},{id:"minecraft:diamond_boots"},{id:"minecraft:diamond_leggings"},{id:"minecraft:diamond_chestplate"},{id:"minecraft:diamond_helmet"}]}}