Yes you absolutely can touch a Rotom (with some caveats.)

You’re right about Rotom’s body being made of plasma, which would burn you very badly if you were to touch it. However, Rotom’s unique ability to possess objects make its relationship to the conventional states of matter very fluid.

You probably learned at some point about the three states of matter: solid, liquid and gas. Plasma is the fourth, secret one they don’t tell kids about for some reason (I imagine it’s because it’s hard to demonstrate. Unlike with the others you probably won’t find objects around the house in a natural plasma state.) Lightning is the most well-known example of a plasma substance and so Rotom in its default state is essentially pure plasma.

However, when a Rotom possesses an object they take an awful lot of solid matter into their bodies. Enough to render them pretty safe to touch. This even extends to the various appendages they gain in these forms, allowing them to manipulate objects and otherwise enjoy the benefits of being corporeal. So, like with the majority of very hot/electrified pokémon, Rotom won’t burn you unless you really upset it.

When not possessing anything, their bodies are usually brimming with electrical energy and as I said, would burn you severely if you were to touch them. It’s much harder for them to regulate the heat and electricity they are putting out, so they’ll likely burn you without meaning to. I’ve known a couple of Rotom who have managed to get some kind of handle on it and that still felt like putting my hand on a stove.

[in reference to this ask] THESE!

I think some people call them potato bread/cakes, but a farl is specifically the kind that’s flat like a pancake and cooked in a pan. Ours are normally square.

Yep, it’s the dry mountain air that will do it.

I’m sure you’ve noticed that static build-up is totally normal for Mareep. Their wool is a fantastic electrical insulator, making Mareep’s body capable of holding a consistant, stable charge for a very long time.

As a result, Mareep are extremely good at subtly managing the amount of electrical energy they’re holding. They do that by frequently discharging a low voltage current along their wool and out via the water in the air. Which is why it’s so easy to get a static shock from a Mareep. So, on a mountain or in any low humidity area, there is less water in the air and the static has no where to go. Which, of course means that it tends to build up quickly and easily.

This is rarely, if ever life-threatening but extreme cases involving high voltage  can lead to injury both for trainers and for Mareep!

(Thanks to physics, Mareep wool is occasionally susceptible to a process called dielectric breakdown. This is when an electrical insulator - such as porcelin or wool - is subjected to such a high voltage of electricity that it goes and turns into a conductor instead. A variation on this process is actually how Mareep shed their wool in the wild, as the current will break the wool down at the root where the wool is slightly weaker. However, a case with excessive voltage can cause burns to the Mareep’s body.)

Thanks for the reply @angst-and-fajitas

If it’s one or two Magnemite at a home or other small building, a good battle to burn off the excess electricity will usually help them cool down. Magnemite usually live in big colonies but sometimes a couple will wander down into a town or city. On their own they are naturally quite timid and once they’ve used a few shock attacks they’ll flee pretty quickly. So as long as they aren’t hurt, it’s pretty easy to handle. The hardest part can be coaxing them out if they’ve backed themselves up somewhere. Small ground-types like Geodude are ideal for this, because any defensive electricity the Magnemite gives off won’t affect them too much. Any pokemon with the Lightning Rod ability is also useful. Small cases are usually caused by damaged electrical lines or fuse box issues and repairing those will stop the majority of repeat incidents.

The trouble is, a lone Magnemite is small enough that it’ll just drift into the vent of a building with a load of electrical equipment inside. Then, because it doesn’t know how the building is laid out, it’ll get lost or stuck. Then it’ll panic and surge or it’ll draw a load of electricity in and end up blowing out someone’s computer or telly. Like with any pest, it’s not really their fault. They’re usually just afraid.

But when a group of Magnemite are overloaded with electricity they can become very hostile. It will also effect their magnetism and disorient them, meaning they lose a lot of control over their attacks. Multiple clusters of several Magnemite in this state can be very very dangerous. So if you end up with a surge or blackout at a lab or any larger building, complex or, in the extreme, a block or district, it’s a lot more difficult to manage. When that happens, we don’t battle them unless it’s strictly necessary. We’ll normally shut down the electrical grid for the area to cut their supply and stop any more Magnemite over-feeding. Then it’s a matter of scouring for the clusters and getting them away from the area as safely as we can. Catching and releasing is the best bet here, as it allows us to give the Magnemite a safe place to discharge their excess electricity.

Thank you for the warm welcome. It's great to meet more local scientists!

I wound up getting invested in Steel-types after a telecoms tower was built just outside of my hometown when I was a kid. The tower brought a lot of new pokemon to the area and all the local kids were catching Magnemite and Voltorb as their first pokemon. I had a reputation for being something of a science geek, so some of my neighbours came to me when their pokemon were sick or injured. This was how I figured out that a lot of general care tips for pokemon don't always apply to Steel-types and it sort of grew from there.

The lab is on the west side, down past the Budew Drop Inn on the high street, where all of the iron and steel works buildings are. The lab is actually a re-purposed foundry. I think it used to be owned by Lapras Shipwrights a decade or so ago before they moved. My predecessor did all of the hard work converting it but the place has been out of use for a good few months so I'm trying to put it back in order.