How do aerobatic aircraft land?
The same as any other powered aircraft would - controlling their descent with a combination of pitch and power.

Most small GA type aircraft don't have air brakes, spoilers etc anyway, so that's fairly immaterial.

I'd imagine almost any civil aircraft can be landed quite safely without flaps - it certainly forms part of the standard training syllabus for the PPL and you'd likely be expected to demonstrate a flapless landing on your skills test. The only difference is a slightly faster approach and more nose high attitude.