Tutorials/Summoning jockeys

Summoning a Jockey (A mob riding on top of another mob) can be useful for adventure maps also interesting to experiment with.

Generation
The few naturally-spawning Jockeys in the game include Spider Jockeys (Skeleton riding a spider), Chicken Jockeys (Baby Zombie riding a Chicken, and also a skeleton trap (Skeletons riding Skeleton Horses.

They can be each summoned via commands:
 * Spider Jockey:


 * Chicken Jockey:

Skeleton Trap:

(Mobs can not be summoned whilst riding a horse and stay on the horse after it bucks them off)

Behavior
The "passenger" or the mob on top, will always have control over the mob it is mounted on as of 1.12. This means no matter what the mount's intentions (attacking a villager, for example), the Passenger will always have control over the mount. For example, if you have a Skeleton on the bottom with a Zombie on top, the Zombie will move the mount itself and pursue a villager instead of you(Only if it notices the villager first, like all Zombies). Mobs on the bottom have small resistance, they can move slowly towards their own intentions (attacking a player) but the second the passenger moves the mount will be forced to move to that location.

In a nutshell, the Passenger will behave regularly if they are mounted on a mob, but they will have a speed boost(equivalent to the players walking speed, or the Passengers speed if the Passenger's speed is faster than the players speed.) For example, if you have a wolf mounted on a cow, and you punch the wolf, the wolf will ride the cow towards you and inflict damage, and it will also make nearby wolves (even wolf jockeys) hostile. If a Skeleton mounts a mob, it can strafe (as skeletons do when attacking). The only exception are Endermen. They will teleport away (with the passenger) if a projectile is shot through them. However, if the Enderman is the passenger, it will not teleport away but it can not be damaged by projectiles.

As of 1.12, Skeleton's summoned through 'passenger' or 'mount' will not have a bow. You have to either equip them with a weapon (or item) or summon a skeleton with one pre-quipped.

The only mobs that can move freely even with a passenger are The Wither, The Enderdragon, Bats, Squids, Parrots, and Horses. Passengers have no control over these mounts whatsoever.(Except Horses-see below)

-If a mob is summoned onto a Horse, that mob will have control over the horse until it bucks them off - just like a player. It will never be "tamed" by the mob, and will only stay on for a limited time.

Examples:

A flying Skeleton, you can make the Bat invisible with /effect

A teleporting Creeper. Great.