What about this sentence?
Dummy subject is "they"
"They"" all praised themselves.
"They" = dummy subject.
We normally use the term 'notional' subject when there is also a formal one in the same sentence, to distinguish between them. E.g. It is easy to do it. 'To do' is a notional subject, while 'it' is a formal one.
There are only two words that can function as formal subjects in English - 'it' and 'there'. All other words functioning as subjects would be notional. So there is no need to specify that, for example, 'you' is a notional subject. It is understood.