Except the helmet is not made of adamantium. The helmet is just made of normal steel. It resists telepathy because it has technology wired inside of it. So this is no plot hole.

Hahahahahaha what a hilarious post. Have you actually watched any of the movies or animated series' or read any X-Men comics?

At no point in the entire movie series is it ever said or even implied that Magneto's helmet is made of adamantium. 99% of supposed "plot holes" are simply people like you not paying attention.

I am not a fan. I just happen to enjoy movies. Fans are embarrassing.

There may be a way around this issue given that matter is mostly empty, perhaps expanding or condensing matter on an atomic level or somehow using virtual particles
This involves quantum mechanics which I am not an expert and I would like to hear what they think. When they say empty just how are they defining empty

But guys CAN teleport? Guys can get shot and heal instantly? Women can control the weather?

You guys are really trying to use science to understand a fictional science-fiction movie based on comics. Smh.
I bet you're wondering what a place like this is doing in a girl like me-The Mummy

It deals with Mass and Volume. You can't fill a 16 oz bottle from an 8 oz bottle.
BOHICA America!

Why is that an issue? She does that as an adult as well. Plus, she can imitate smaller people as well.

Yes, such as the 'young' Mystique' being able to turn her little body into Xavier's mother, who was a full-grown adult, several inches taller and many pounds heavier.
BOHICA America!

They break their own rules and physics to further the plot along whenever they want. Kind of lazy.
Bingo

Prof X's power waxes and wanes as needed. Magneto's too. Emma's also.
Emma should have been able to sense Moira when she was spying on them. Especially when she was startled. It should have been like a psychic scream to a sensitive.
When Prof X checks out the Arel Sea ship, he sees through the mind of it's captain, whom Azazel kicks in the head to knock him out. Why not just take over Azazels mind right there? He's not protected.
Professor X should have been able to freeze the entire fleet and steal Shaws Helmet by controlling Azazel. He's frozen large groups of people before(an entire airport in a preview scene), and still been able to control people at the same time.
Here they do a cute little thing, having him touch his head to activate his power. Something Emma doesn't have to do?
Magneto shattering Emmas Diamond neck with a brass bed?
They break their own rules and physics to further the plot along whenever they want. Kind of lazy.

I think the concept is similar to a Faraday cage, and it wouldn't necessarily have to be made of a particular metal just one with this property?

Magnetos helmet is not made from adamantium and it's never said in any movie that it is.