In CTF the Blue Team can see monsters just fine. They will dodge them and fight them and kill them.
The Red Team are completely oblivious to the monsters. Even if they get shot or hit by them, other than losing the health they don't react.
Monsters like the UTMDT, Talking Titan, the Reds can see... but then he's really just a big bot.
I've been playing around with TeamMonsters.u

Only tried Krall so far, after giving them better colored skins like here.
Why can't the Red Team see monsters?