adversary
nemesis
Nemesis is a word for arch rival.
An arch rival or enemy might be your nemesis.
Nemesis is the best choice. Other words could be enemy, adversary.
nemesis
Mario's arch rival is Wario.
We play our arch-rival next week!
Arch Rival Rollergirls was created in 2005.
Not a rival... an arch-nemesis!
Gator
The Comanche
"She will be competing against her arch-rival in the upcoming tennis tournament." "Tom and Jerry are portrayed as arch-rivals in the popular cartoon show." "The two companies have been arch-rivals in the smartphone industry for years."