What is the carbohydrate found in almonds, cashews, pecans, hazlenuts and pistachios?
Firstly you must realize that all the above mentioned nuts are actually the seeds of plants.

So the question now is which carbohydrate is mainly found in seeds of plants.

During the double fertilization of angiosperms, one sperm fertilizes the egg to form the embryo while the other fertilizes the endosperm nucleus to form the endosperm which acts as the nutrient storage for seeds.

The major carbohydrate for seed endosperm is Starch, often stored as granules for their property as being insoluble and compact.

However there are other carbohydrates such as free sugars, glucofructans and hemicelluoses present.

Hope this helped.

References
https://link.springer.com/chapter/10.1007/978-1-4615-2672-8_8