If there is one thing we all know about oozes, it is that they are gross and slimy... and there just aren't enough of them. The only monster categories that has less monsters in them is Celestial, and that's only if you count all the "Reduced-Threat" templated oozes found in the adventure Dead in Thay (and I don't). But I get it, oozes are gross slime monsters, and how many gross slime monsters could you really need? I, personally, need just a few more to gross out and sicken my tables...
Giant Amoeboid (CR 9) Amoeboids are gross and large and really off-putting. They are unicellular organisms that just go around and engulfing other unicellular organisms. But what happens when you accidentally turn something microscopic into an uncontrollable gargantuan blob? I blame wizards.
Blood Sludge (CR 6) Another name for this could be a coagulated blood pudding. This foul ooze is on the hunt for living creatures to siphon their lifeforce and feed on their blood.
Detritus Ooze (CR 5) My first thought for its name was shit ooze, but I decided to be a mature adult about it. This ooze is created from offal, fecal matter, sewage, waste, and anything else that you could scrape out of a medieval sewer system.
Psycho-Slime Ooze (CR 3) Yes, I recently rewatched ghostbusters 2 - why do you ask? The psycho-slime is excited when everyone else around it is excited, feeding off their emotions like panic, anger, fear, and intense pain. It can't help that it hungers for extreme emotions.
Plasma Ooze (CR 8) Cast offs from the sun, the plasma ooze is a force to be reckoned with as it gives off intense waves of heat and crackling electricity.