The phrase "always been a formidable" is correct and usable in written English.
It can be used to describe someone or something that has consistently been impressive or powerful over time.
Example: "She has always been a formidable opponent in any debate, never backing down from a challenge."
Alternatives: "consistently been a powerful" or "long been a strong".
LONDON — Germany's Mannschaft has always been a formidable soccer team.
Reconstruction of the vagina has always been a formidable surgical challenge.
It has always been a formidable barrier between Battery Park City and the rest of downtown, but now it is crossed by four bridges from Chambers Street to Rector Street, a distance of less than a mile.
Because this species is a self-pollinating allotetraploid (AABB, 2n = 4× = 40) with a large genome size (2800 Mb/1C) and a narrow genetic base, leading to very low DNA polymorphism, the development of molecular markers and genomic resources in peanut has always been a formidable task [ 1– 3].
In aligning himself with St Francis, the Pope addresses what has always been a gaping hole in the formidable Judaeo-Christian moral tradition – the absence of reverence for the earth itself (in contrast to some other religions, such as Buddhism).
The Mariners have always been a team that could use another formidable starter to prevent them from fizzling in October, and Meche could wind up being that starter.
History's most formidable figures have always been a tough act to follow, of course.
The Andes always have been a formidable barrier for communication, with great effect on the economic and cultural development of the region.
Mr. Ruff, leaning forward in the wheelchair he always uses, was a formidable presence behind the witness table.
While he possessed bags of natural talent, Jackson has always maintained it was a formidable work ethic instilled by his parents, first generation Jamaican immigrants, that marked him out for greatness.
As you know, I always said Clegg would be a formidable opponent.
