Well, certain ghost-types may induce this in sensitive people, as their general presence affects humans on a more psychic and spiritual level. For example, a particularly sensitive person can tell that members of the gastly line are present because they inherently evoke a sense of dread. The same can be said for misdreavus, mismagius, the duskull line, and spiritomb. On the other hand, many others who are less psychically inclined have no trouble handling ghost-types, so whether or not they would induce or promote anxiety in a human being really depends on the human themselves.
Meanwhile, poison-types who emit gaseous toxins actually do this more reliably, meaning these will affect most people, regardless of whether or not you’re sensitive to poison-types. The reason why is because the toxins actually affect us humans on a physical level by interacting with our respiratory systems (and thus, everything from our immune systems to even our skin, digestion, and so forth). In turn, this can induce anxiety because, well, the more our bodies react to pollutants, the more our minds react to the warning signs that we’re breathing in toxic air. It’s very much akin to living in a city full of smog and pollution for prolong periods of time: while it’s possible for you to exist that way, you may find that you’ll feel more at ease when you escape to the country and get some fresh air, so to speak.
This isn’t, of course, to say that it’s impossible or not recommended to train a poison-type (or even a koffing or weezing). Many people who own such pokémon find that they’re perfectly happy with their companions. It’s just that it’s highly recommended to give yourself and your body a break from them, especially if you notice changes in your physical or mental health.
(Also, their gases are literally carcinogenic, so don’t plant your face in your weezing, regardless of how tempting it may be.)
The Pokédex According to Bill 