Not sure what folks are waffling about this my TL of the relevant bits of the chapter.
Giant: In addition to Roger there were two pirates in particular that were absurdly strong that stood out from the bunch
Ussop: In addition to Rayleigh, you’re saying there was one more!?
Giants: Yes~! One upon a time…
Giants: Alongside the Vice Captain Rayleigh, he was referred to as the left hand of the Pirate King.
Usopp: Wha!!!?
Giant: I’m telling you! He’s here ! He’s been residing on Elbaf for more than 20 years now
Usopp: Really!!?
Giant: He was a legendary key figure that stood shoulder to shoulder with Roger & Rayleigh!!
Giant: The left hand of the Pirate King…
Giant: Scopper Gaban!!!!
Should be obvious but from the TL on the first page, Oda establishes Scopper’s strength & status in comparison to Roger & Rayleigh
And with the second phrase 「肩を並べた」bunches all 3 of them together. The word "equal" wouldn't be my choice of words here personally but it is in the definition of that phrase so can understand why some scans or TLs used that. Nuance here should pretty obvious regardless though
https://dictionary.goo.ne.jp/word/肩を並べる/
Definition of the phrase can be found here.
Can always ask anyone that can speak JP to TL it for you