When he has the voice of a baritone and the dynamic range.
Granforte, Bastianini, Cappuccilli, Gobbi, De Luca , Merrill, Warren and Mac Neil, were all fine examples of baritones.
Mattia Battistini has always been something of a mystery to me. He had a voice to be sure, he had a beauty of tone in the middle voice, but he was lacking in the low register (as was Warren) and his habit of shifting pitch and taking liberties with the music and the line was curious to say the least. He was also a shocking Mozart singer, with next to no regard for style or for the music as written .
He switched tone sometimes as he went up, in fact, it sounds as if he raises the larynx, certainly there is a "bleating" sound at times which grates on me. I am sure he was considered great in his day, he was an impressive looking man with a unique sound in a time when to be an opera singer was to be a huge star in the eyes of the masses.
Isaac Allen, Opera L
Battistini was a high baritone. Verdi wrote several roles for him, in fact. When one says Verdi baritone, Battistini is the type. Whether recordings do him justice is a good question. He seems to have been a great technician with a good voice, and a singing actor. People were nuts about him.
Verdi wanted to work with Faure but he refused the roles as too high. He would be more what we think of as a bass baritone.
There is such a type as the Baryton Martin, an even higher category, but still a baritone or an in between voice.