Gama had a lot of size and strength on his side. Pesek was arguably better pound for pound.
Pesek was 70-0 after he won the world title against Wladek Zybsyzko who had a claim to the world title of the then late Frank Gotch (Ed Lewis and Joe Stecher also laid claim to the title and the 3 wrestled each other several times with varying success). Zybsyzko was also a Greco-Roman champion and had a 35lbs weight advantage on Pesek.
Pesek beat Zybsyzko in the first 2 out of a best of 3 falls match. 3 weeks prior to this world title match, Pesek beat the US Army Champion Corporal Chris Sorenson also in the first 2 in a best of 3 falls match. The first fall took 64 minutes to win.
Ed Lewis (also claiming to be world champion, along with Stecher) and Billy Sandow decided to hire Pesek as a 'policeman' to basically beat anyone seen as a threat to Lewis. This means Lewis who many still think is one of the greatest of all time, feared he would lose to certain people and that he wanted Pesek to wrestle and defeat them instead. Some of these threats included Jack Taylor (Canada), Charlie Hansen, Olympic Champion Nat Pendleton and Armas Laitenen of Finland and Pesek beat them all so they didn't get to wrestle Lewis for his title.
Lewis had been upset in a match by Stanislaus Zybyszko, and Zybyszko was meant to drop the title to Wayne Munn a famous football player with no actual wrestling. The match was meant to be a work promoted by Lewis, but Zybyszko was secretly working for rival promoter (and other world champion) Joe Stecher. Zybyszko decided the match would be real and destroyed Munn obviously. Zybyszko was well past his prime and lost legitimately to Stecher a bit later. Pesek had parted company with Lewis and Sandow.
So at this time Pesek was still undefeated and had one world title, Stecher had two titles - the one he claimed and the one he won off Zybyszko (who won it off Lewis).
Pesek would wrestle Stecher in a war. Pesek won the first fall by pin, Stecher won the second by pin controversially as some claimed he used an illegal choke hold to help get the pin. In the final fall Stecher threw Pesek violently out of the wring and Pesek was injured and couldn't continue. It was Pesek's first legitimate loss (not counting the 'loss' in a 1 on 3 handicap where he claimed he could throw all his opponents out of the ring but one of them held on to the ropes for dear life and wouldn't be budged).
Stecher was the undisputed champ and Pesek wanted a rematch but had to get a couple of more wins under his belt. He would wrestle and beat Jack Taylor (who had a 40lbs weight advantage) and Nick Lutze, the Notre Dame wrestling champion Pesek had beaten a year or two earlier.
With these wins Pesek earned a rematch with Stecher at the Olympic Auditorium in Los Angelese on October 6, 1926. Stecher was 214lbs, Pesek was 185lbs to 190lbs and had been regularly beating men who were 40-60lbs heavier.
It was thought this match was meant to be a work, the first fall by pin going to Stecher, the second by pin to Pesek. In the third fall Pesek repeatedly pinned Stecher but the referee refused to make the pinfall as Stecher was meant to be winning. Pesek trapped Stecher in a headscissors / double wrist lock combo.
The referee tried to claim Pesek was illegally choking Stecher but Pesek told Stecher "Joe you either give up or I'll break your arm" and forced the referee to award Pesek the match and Stecher was left crying in the ring.
In true pro wrestling fashion though, the referee never officially announced the decision and the decision ended up being overturned.
Pesek had contempt for the increasing number of works in pro wrestling and the business generally so he travelled to Australia and New Zealand and won 47 consecutive matches. Every title he had won he kept.
Pesek returned to America and was recognised as the Midwest Wrestling Alliance champion from 1931-1933 but was stripped of the title after he left to go to another promotion, Pesek twice won the NWA championship but was stripped for supposedly no showing matches although it was more likely promoters were afraid if he won their titles they'd never get them back.
So, Pesek beat two of the best of all time, was the linear world champion (despite being screwed over), lost only 1 fight and that was by injury, and beat guys who often outweighed him by 40-60lbs. It's a pretty solid argument.