I think you’re getting confused with dark energy. There is very little debate about dark matter–it’s an observation that many many many people have made.
Dark energy is the name for whatever is causing the explanation expansion rate of the universe to increase. There’s quite a bit of debate about whether the expansion rate even IS increasing. And the amount of increase is different according to how you try to observe it. So yeah, there’s a lot of debate about whether dark energy is actually a thing, but there is very little debate on whether there’s more matter than we’re able to observe, something that we call dark matter but which we don’t really understand. Similar names, but totally different concepts!
You wouldn’t call a person a dwarf, period. So don’t do that. If you ever meet a little person, they’ll probably refer to themselves as a little person. You should just follow their lead
A dwarf planet is not a category of planets. It is a category of sub-planetary objects. This is how the term “dwarf planet” was adopted by the IAU in 2006. It did used to mean “type of planet”, but there are just too many of them, and they’re really too different from planets, so it literally does not mean that anymore. At least to astronomers.