“Phillies” is perfectly serviceable as a nickname, evoking the team’s home city. However it’s bland enough that both team officials and fans have tried to introduce a new name for the team from time to time.
According to baseball-reference.com, the team that entered the National League in 1883* was known as the Quakers. There’s some debate about that though, and it’s not clear that “Quakers” was used any more than “Phillies”:
First, nicknames were not official monikers used by major league teams until the 20th century. In the 19th century, nicknames were created and used by newspapers.