Per Moesh's comment on MC-46956, I'm making a new report for this.

Some entities harm teammates that walk into them, when friendly fire is false

Steps to reproduce:

1. /team add TestTeam
2. /team modify TestTeam friendlyFire false
3. /team join TestTeam
4. /summon slime ~ ~ ~ {Team:TestTeam,Size:3}
5. walk into the slime
6. notice how you take damage

Affected entities:

• Slime
• Magma Cube
• Ender Dragon
• Pufferfish
• Area Effect Cloud (added for inclusion purposes; it's understandable if this one is WAI)

Expected result:
Friendly fire is respected and they cannot hurt teammates.