In my friend's server I am an admin and I needed to summon in a no AI, silent bla bla bla mob, the only problem of spawning a villager or a chicken, etc is that they start bobbing up and down as if they had a "space bar".
And before updating the server to 1.10.2 (1.9.x) It wasn't doing that you would just get a still and silent mob as part of a decoration or a minigame whatever.

Hope you can fix it