In chess composition there is the Fairy Chess, where we see other conditions, others pieces, other chessboards.
For the question "which fairy elements are mostly used?", a statistic comes to our help, based on the about 785,000 problems that are contained in the database WinChloe by the French Christian Poisson.
The statistic is published in an article of the very good composer Julia Vysotska:
It is important to remember that the fairy elements were not defined at the same year, so the older elements had for more time the opportunity to be chosen for use.
The statistic shows that there are about 2670 fairy elements (pieces and conditions) and in the first position stands the piece Grasshopper (introduced in 1913) with 14073 compositions containing it!