Which country gained the most from imperialism in which country suffered or lost the most

The British, by far. Their empire spanned the U.S Colonies, Canada, India, Middle East, Australia, Caribbean islands, and Africa. The mercantile economic system, naval strength, and early industrialization allowed them to dominate despite setbacks such as the American Revolution.

"a government in which power is divided between state and national levels". federalism is a system of government in which entities such and state and province, share power with the national government.