In the order of appearance , here are some variations of the Boggart.
Arctic Boggart -
I chose to make this variation because of the Boggart's culture, he is situated in the northern countries, UK, Greenland, Norway even Siberia.
His biggest adaptation is growing stronger resistance to cold, he also makes fur clothing out dead animals. He is to afraid to kill, so he scavenges. His stomach adapted very well, it makes stronger acid to dissolve rotten meat and bone and his immune system got stronger compared to his relatives.
It's quite weird but, uses small bones and sticks to ornate his beard or hair sometimes. It kind of makes him more relatable to, kind of human if you might say.
Swamp Boggart -
Because of his swamp humid habitat and his hard wrinkly skin, The boggart is very likely to have some vegetation growing on him, something like mushrooms , moss maybe or small plants. Sitting there all day, in the marsh water is very unlikely to not have some skin problems of some kind.
In the depths of the ocean, there are whales that have barnacles attached on them, they don't harm it but are often seen on their bodies in large patches. The Boggart usually has them on his shoulders and back, feet, hands and forearms and uses them as camouflage.
Rural Boggart -
This type of Boggart is very different and very rarely found than the others. His is not hugely different as appearance, he lost almost al his body hair , look human like but in terms of behavior he is very particular.
Living near humans thought him to disguise himself and to steal. That is huge, he steals clothes from people and acts like beggars do, for food mostly. He can't speak very well, so buying food with the money he was given is not his way. The shyness and fear of others has not disappeared along with the hair, he is the same at his roots.