Here is an overview of the game, via the 3DS version’s Nintendo.com page:
Ambition of the Slimes is a turn-based strategy RPG that controls the slimes to battle.
Different kinds of slimes have their own abilities, you have to choose the proper slime to take over the enemy and consider how to battle with them.
Many tactics can be used in battle and your choice is the key to victory. Try another method if you cannot defeat your enemy because the slimes are too weak to battle by themselves.
Watch the Switch version trailer below.