"Prob Garp and the others battled the crew and Roger (like Luffy) rushed to Rocks and beat him"
lol "prob"
am not ready to look into your assumptions on how they fought.
the wg gave credit to garp solely but sengoku when he states garp and roger took rocks down together is entirely telling the truth of what happened .
literally tells you the truth is before stating garp and roger joined forces to take down rocks . thats all we know, staing this matchup happened or the other didnt is purely headcanon till a flashback is available.
kaido wasnt as strong back then (no fruit)
big mom likely wasnt either
being a rival doesnt mean roger took him down solely lol.
shiki was roger's rival and was beat by sengoku and garp.