To further elaborate, depending on what fish you are going to breed in the breeder tank, determines what should be in the tank.
For example, When I bred Angelfish, All that was in the tank was a piece of slate, a sponge filter, the heater and the fish. With barbs and tetras, I had live plants over a breeding grid and no filter at first just an airstone. Fish such as Kribensis and Rams had Flower pots in the tanks along with sand substrate. Oscars and the bigger cichlids had large flat rocks along the bottom with no substrate.
So you see, a breeding tank needs to be set up for the fish you are going to breed in it. There is no one answer for all the fish you can breed
Hope I didn't confuse you