A "formidable challenger" refers to someone or something that is extremely strong, powerful, or skilled, making them difficult to beat or compete against. Full definition
All the films up for Best Picture are formidable challengers in their own right. (awardsdaily.com)
One of the S8's most formidable challengers is now unlocked, too, and you save up to $ 100 depending on where your order it from. (tomsguide.com)
And, it wants to become a more formidable challenger in data storage, a goal that can be furthered by buying Permabit's technology, Fichera said. (fortune.com)