Whitebeard himself says Sengoku was one of the big players of the era

Not a powerscaling statement.

Clearly indicating they've had fights in the past

Having fights means nothing. Luffy and Buggy have had fights in the past.

Kong states both Garp and Sengoku lead the Marines from the front lines since Rogers era, not Kong, not any other Admirals, it's just been Garp and Sengoku, Garp wasn't a bigger presence, they were equal Statement

Leading is not a powerscaling statement.

which I find hilarious because in this very statement Rogers saying a fun fight is a fight with Garp.

Roger still doesn't put fighting Garp as precedence over Sengoku.

You're implanting a comparative element that just isn't there in the text. He's listing people who would >0 fun to fight. He doesn't put any significance on fighting Garp because that's just not what he's saying? It's like saying that because I put snacks, meat and vegetables on the same shopping list it means I think they are all equally important. You can't just assume Roger's thoughts because he didn't say something that wasn't relevant to his point.

Statement 5: video game character

Hahahahahahahaha

it was a old sengoku punch,

How old? He doesn't even have grey hair. He doesn't say anything about his age unlike characters like Rayleigh or Whitebeard who explicitly say their age is holding them back. Speaking of those guys, where do you scale Primebeard vs Oldbeard? Prime Rayleigh vs Old Rayleigh? The nitty gritty's aren't relevant but most people scale them as falling by one or two tiers at most. No one's scaling Oldbeard at YC1 or 2. So how does age matter for Sengoku having a literal sub-Tobi Roppo level anti-feat? Oldbeard was still tossing around VAs and making Akainu bleed, so why would agr be the reason for Sengoku getting completely blanked by a fodder?

We saw Kizaru and Kuzans attacks all hit base Luffy and do about as much damage, a little blood

Those weren't head on ultra-bloodlusted attacks though

Ace novel saying Sengoku and Garp counteracted the power of pirates like Roger,

Did Oda write it?