The Fonz, also known as King Fonz, is a Nidoking in Red's party that got his name from his distinctive nickname.
History
The Fonz was originally a normal Nidorino from the Safari Zone. After the events of Bloody Sunday, ATV and The Fonz quickly became mainstays of Red's party afterwards.
During the events of the Pokemon Mansion, The Fonz was the only Pokemon able to resist the constant poison and fire attacks coming from the wild Pokemon there. When Red became trapped between a table and a Burglar Trainer, the mob planned to white out the entire team in order to escape, but because the Fonz was so resistant to everything, it took a while before the Mob escaped this trap.
One of Fonz's most notable achievements was near the end of Victory Road. As Red approached the exit, he walked into the vision of an opponent, and a battle began with the entire party wiped out with the exception of The Fonz. Despite being up against four opposing Pokemon solo (and being underleveled as well), the Juggler's unusual strategy of constantly swapping allowed The Fonz to wipe his team. Thus, Red was able to exit Victory Road and make his way into The Pokemon League.
Name
Fonz's name of several 'A's reminded players of the catch phrase of the Fonz from the popular television classic, Happy Days. It didn't take long for the community to start calling him Fonz, which over time evolved into 'King Fonz', to match is associated role in the party according to most lore, the King. This was compounded by the fact that like all Nidokings, the Fonz evolved with a Moon Stone—he was a Moon King.
Lore
Overtime, much of the lore began to focus on the roles of the main members of Red's party. Because the lore had began to turn to a holy quest, soon players felt that royalty would fit in with the party. Eventually, Fonz took the role of King, while Air Jordan took the role of Prince.