The fusion of Dunsparce and Hypno (or, alternatively, Dunsparce and Deino). Dunno what else it could mean.
Person 1: What would a fusion of Hypno and Dunsparce be called?
Person 2: …Dunno.
Person 1: That’s it!
British slang for hello or hi it's used as a type of greeting
ayo what are you doing dunno
Another way of saying " you already know"
You dunno she got an A+ on her test