If anyone laid the foundation for wrestlers and how they condition themselves in the sport, it was arguably Wrestlers from the Middle East & India hands down. They taught the fundamentals of how to utilize the body to such a degree that stamina was inexhaustible, strength lasted for hours on end and being explosive was inevitable at any given time. They created what is still being used today just through certain variations.
The thing is, not every wrestler or coach uses the same exact exercises or even principles of their training to be successful in the sport. Some conditioned according to their size and what gave them the tools to be successful. Now in modern times when it comes to conditioning or even more specific, bodyweight conditioning, there were the three main forms of exercises that were the ground work; the pushups, the squats and the bridges. Those were the pinnacle aside from actual wrestling but there was more to them or in better terms, what other wrestlers and coaches took into consideration that honed the skills and the ideal training methods.
Every culture since ancient times has their hand in wrestling in some form or another and formed their own ideas on how to condition the men to fight in order to be dominant in a tribe, kingdom or just a village for that matter. In Mongolia you didn't see wrestlers do Hindu Pushups or do Hindu Squats in order to condition, yet some of these were so powerful, it was unbelievable. There were cultures that if you look throughout history, probably didn't do a single supplemental exercise and just wrestled and were just as strong and dominant. Look up how Senegalese Wrestlers sometime and check out their methods.
In America, you had some of the best wrestlers in the world that came from everywhere and took their skills to places that just baffled onlookers. Some of the greatest in history utilized more of a weight training approach, some used a mixture of bodyweight and weights, bodyweight alone and some either ran or just wrestled in order to get in condition. The fact of the matter is, regardless of how you wrestled, you used basic exercises and often times compound movements to be successful. Once Karl Gotch came into the picture, his use of the Hindu Style became a requirement in most wrestling gyms since the 60's or even as far back as the 50's when he was being groomed but if you look at the ideals of conditioning the body for the sport, at least from an American point of view, the Hindu Style wasn't written up as much if at all.
Although many exercises can be traced back to the Hindu Style, you didn't see their version of the pushups & squats along with others in the old Physical Culture courses from the likes of Farmer Burns, George Hackenshmidt, Bernarr McFadden, Earle Liederman and others. At least two of these guys were very successful wrestlers in their time but you never saw the Hindu Style of conditioning. Also with that in mind, wrestling styles vary from culture to culture. Mongolia had more of a Greco-Roman/Judo type style, Senegal was grappling mixed with boxing or bare-knuckle type fighting, Hindus were a close relationship to our modern Amateur Wrestling and today's Catch Wrestling is utilized with Submissions and overall base of takedowns, suplexes and throws. Then you have styles from Turkey, Brazil, Japan and Russia that vary the rules of combat.
Is the Hindu Style the very best? That all depends on the coach and what they're willing to teach students of the art. It certainly works in many aspects but if it was the very best, every wrestler since the dawn of man would do it but they don't. Today's aspect of conditioning for MMA still has its roots that trace back to India but with the concept of utilizing more explosive based conditioning than just stamina and strength based, there are countless ways to be a successful combat athlete or even a wrestler for that matter. The Hindu Style works without a doubt but there should be options to how we base our training according to the needs of the athlete. Look at the success of Dan Gable and the University Of Iowa, their style of conditioning wasn't like the Hindu Style but what did they produce? Some of the greatest wrestlers that went on to Olympic glory.
Last thing, there are wrestlers out there that are so fanatical on conditioning they base their livelihood on it. I do believe the better condition you are, the higher chances of being successful but it's not always the supplemental stuff that will get you there, hell even Ed Strangler Lewis had said that wrestling was the best conditioner and despite the fact that he wasn't shredded or had the body of a Greek god, his stamina was the stuff of legends. The man in his prime just didn't know the meaning of the word "tired", he can go for hours and be practically just as efficient towards the end of a match as much as the beginning.
You be the judge, what do you feel makes a successful wrestler?