Got two chameleon armor pieces, one is a chest piece bought in the institute and the other a reward and both work in character, but when one is placed on a companion it doesn't work. The companion tested was Deacon.

Pretty sure it's a visual glitch - they still get the stealth bonus, as far as that goes with Companions. They're still terrible at stealth unless you give them full shadowed/muffled gear - then they're elevated from terrible to less-terrible.

If I want to go full stealth, I go alone.

Not sure, but I give Piper this:

- Chameleon Leather Arm

- Chameleon Combat Armor Leg

One of them didn't and never worked. I assigned both, but I have to re-apply everytime I reload the game, then the Chameleon effect will work.

Seems like only Nick Valentine uses different weapons at choice. The others (MacCready, Daecon ..) they just use a default unless a weapon is specifically equipped which they then use. The dog and Cosworth are melee. So Nick is the most intelligent AI?

Piper, Curie, Nick will use anything they want.

Not sure about MacCready and Deacon. Seems like MacCready tend to choose rifle type, so far I noticed.

Danse will use laser rifle and always that.