/summon MushroomCow ~ ~ ~ {ActiveEffects:[{id:14,Duration:100000,Amplifier:1,HideParticles:1}],Riding:{id:"Spider",Attributes:[{Name:"generic.maxHealth",Base:10000}],Riding:{id:"Villager",Attributes:[{Name:"generic.maxHealth",Base:10000}],Riding:{id:"Spider",Attributes:[{Name:"generic.maxHealth",Base:10000}],Riding:{id:"Bat",Attributes:[{Name:"generic.maxHealth",Base:10000}]}}}}}
Explanation:
I used a spider to separate the mobs in the end as it's exactly 1 block tall. It is invulnerable to suffocation (because it has like 10000 health).
Also, all mobs have 10000 health, so even when they are stuck in a block because of the bat, they don't die. Change health by changing the number of baseHealth in this section: Attributes:[{Name:"generic.maxHealth",Base:<HP>}]
To kill the whole stack, first off, you have to make sure all commands blocks are activated at the very same time -- exact same time, or it may result in idling totems of mob towers. Then type in the command /kill @e[type=Bat,c=1,r=<size of the field>] in command block A, /kill @e[type=Villager,c=1,r=<size of the field>] in B, /kill @e[type=Mooshroom,c=1,r=<size of the field>] in C and /kill @e[type=Spider,c=2,r=<size of the field>] in D. Then you should be able to kill the whole stack.
I don't have a computer now so I cannot check the code, but feel free to tell me if it worked or not. Thanks!
Best Answer
/give @s repeating_command_blockexecute as @e[type=villager,tag=baby,nbt={Age:-1}] run data merge entity @s {Age:-1000000}(remember to finish with Done)/tag @e[type=villager,sort=nearest,limit=1] add babySetting the age to a very low negative number is only a temporary solution, for example your
Age:-1000000would expire after about two weeks. My solution keeps working forever.