VISION: Each student demonstrates strength of character. and is college or career ready. MISSION: The Bibb County School District will develop. a highly trained staff and an engaged community dedicated. to educating each student for a 21st century global society.
Slimes spawns normally like other mobs. Slimes will spawn in swamp biome, flatland or anywhere if the game glitches out. Of course it will also spawn out of the slime spawers.
Mobs will spawn only when you want them to. If you're really committed to the idea of doing this with /kill, however, you can do this one of two ways. You can set up individual command blocks to kill each type of mob, which might be a small set of command blocks if your main problem is slimes.