Well it is stated that he was alive in the first and second ages. He slew a balrog during the escape from the sack of gondolin. Not sure about the other stuff though.

I really wondered the source of information about other battles.

I’m pretty sure Tolkien doesn’t mention the other stuff. It could be guessed that any battle that the hosts of gondolin were in he was in.

He was a Captain of Gondolin, therefore i guess people think he took part in most of their battles by conjecture.

Haerangil said it best