Montell Griffin Virgil Hill Yaqui Lopez Marvin Johnson Could Walcott go 4-0? This is prime mid 1940s Walcott vs prime versions of these men?
With ease just don’t send in Sugar Roy Jones! Unless you’re going to flip the cleaners bill. Seriously can this stop?
At his best he would beat them all on the same night. Walcott is not always remembered as well as he should be because he took fights on short notice, fought on and empty stomach, possibly threw a few, and got cheated out of his biggest victory in a fight against Joe Louis where over 2/3 of writers thought that he won. But those in the know know that he was a first class great in talent, with both power and awkward, tricky style in which he played the puppeteer.
If we're talking after the well-connected Felix Bocchiccio became his manager then it's possible he wins all four. However, beware the betting interests lurking in the background.
In a fantasy scenario if you could have Walcott at his absolute peak in all 4 of those fights then yes I'd favour him to beat all 4. But considering Walcott lost 20 times and has lost to far worse fighters than the 4 names above. Realistically I would say Walcott going 4-0 in a real life scenario is not likely.