Zombie Jockey: /summon Zombie ~ ~1 ~ {IsBaby:1,Riding:{id:Chicken}}
Pigman Jockey: /summon PigZombie ~ ~1 ~ {IsBaby:1,Riding:{id:Chicken}}
zombie chicken jockey in full diamond armor, with a diamond sword: /summon Zombie ~ ~1 ~ {IsBaby:1,Riding:{id:Chicken},Equipment:[{id:276},{id:310},{id:311},{id:312},{id:313}]}