Gary Oak and Blue Oak are two of the most well known Pokemon characters. Contrary to popular belief, they are not the same character. Similarly, Ash Ketchum and Red are not the same character. It is generally accepted the Gary and Ash are Blue and Red's anime counterparts respectively. Blue Oak is the player character's rival in the original games Pokemon Red and Pokemon Blue. While Blue is a completely different character from Gary, they do have many similarities.
Since Blue and Gary are considered counterparts of each other, there's a long-running debate between fans on who is the better trainer. Does having more gym badges make one a better trainer or does one have to become a Pokemon League Champion? Do either of these things matter in the grand scheme of things? Read on to finally settle the debate of who is the better trainer.
Major Similarities
Gary Oak, or Shigeo in the Japanese version, was based on Blue, or Green in the Japanese version. While they aren’t the same character, they are incredibly similar in many ways. Looking past the physical similarities, their personalities are nearly one for one at the beginning of the series. They both have the signature phrase of “Smell ya later!” Blue does say this more often, but Gary can be seen saying it as well. Gary, like Blue, always seems one step ahead of his rival. Both are Professor Oak's grandson.
Despite Gary saying something along the lines of “Oh, you’re Ash?” when they see each other in episode one, it is confirmed that Ash and Gary are childhood friends in the episode "The Bind that Ties." In this episode it's revealed that they both kept half a pokeball they found together as kids. Likewise, Red and Blue are also childhood friends. It's revealed at some point in the game that Blue became meaner to Red as they got older and somewhat drifted apart.
Sportsmanship
In the beginning, both characters have incredibly poor sportsmanship. Gary parades around the first episode with a cheerleading entourage and makes fun of his rival in front of the town. They are ten-year-olds, but it's still pretty terrible behavior for someone about to embark on a lone journey. Blue, on the other hand, isn't much better considering he refuses to acknowledge the skills of the player character for most of the game.
Blue's attitude and sportsmanship do get better later on, as does Gary's, but Blue's attitude change happens much later. Blue doesn't seem to mature until accepting the gym leader position while Gary matures before his Pokemon trainer arc is over. Gary even encourages Ash after he loses, hoping his friend wins when he himself couldn't. Considering Blue doesn't take his championship defeat at the end of the game very well, Gary definitely wins out in the sportsmanship category.
Pokemon
Blue and Gary both have a variety of Pokemon. Surprisingly, the Pokemon Gary uses throughout the series have some similarities. For those who haven't played the Pokemon games before, your rival will choose the starter Pokemon that you are weak against. Because of this, Blue's Pokemon change slightly depending on the Pokemon the player chooses.
When comparing the first game to the first few seasons of the anime, viewers might notice that both Gary and Blue (potentially) use an Arcanine. The biggest difference in Pokemon seems to be that Gary has caught more Pokemon than Blue according to the games. According to the manga, Blue has caught 147 Pokemon before battling the Indigo League, which would put him above Gary in that aspect.
So Blue might have more Pokemon than Gary, but what about how they treat their Pokemon? In the original games after the player character defeats Blue, Professor Oak finds them hoping to congratulate his grandson. By the time he gets there, however, Blue has already lost his champion status to the player character. Professor Oak explains to Blue why he lost saying: "You have forgotten to treat your Pokemon with trust and love!" On the flip side of that, Gary is praised for how well he treats his Pokemon with Misty and Brock commenting on how nicely he treats his Eevee. Ash, on the other hand, is actually reprimanded for this at one point in the series. While Blue might have more Pokemon, Gary treats his better.
Gym Badges and Battles
In terms of badges, Gary actually wins that category with at least 10 badges, while Blue has 8 badges. While Gary and Blue both travel and win many battles, only one of them ever defeats a Pokemon League and becomes Champion. As mentioned previously, that person is Blue. Considering Gary's track record of losing Pokemon Leagues, he probably would have lost more Pokemon Leagues had he stayed a trainer.
Another important aspect of their Pokemon Journeys is that Gary actually quits being a Pokemon trainer while Blue goes on to be the Viridian Gym Leader. Gary might have more badges, and might have treated his Pokemon better for the better part of their journeys, but Blue might be considered the better trainer when compared to Gary. It's actually mentioned by Misty in the anime that being a Pokemon trainer means more than making friends with your Pokemon. You have to be able to train them to be strong as well. Gary can train them, but not well enough to defeat any Pokemon leagues. Over time, Blue also becomes more mature, which makes sense considering he becomes a gym leader eventually.
Conclusion
To recap, Gary seems better in sportsmanship, Pokemon care, and badge collecting. On the flip side, Blue is better at training, has actually beaten a Pokemon league, and becomes a gym leader. Both of them mature eventually and go on to do great things in the Pokemon world. One of the best things a trainer can do to be "the best" is to become a gym leader. While both characters are great, Blue is likely the better trainer by a slim margin.