These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
In the first season, Lee was an absolute beast who could copy his teammates techniques and always won easily before his match with Ray and Tyson. But in G Revolution, he's overly emotional and drives himself way too hard and in general, is just nowhere near as impressive.
Ray briefly seems to come under this during the American tournament in season 1. After serving as the central character in the China tournament (even winning his team the final battle against Lee), he's relegated to only participating in three of the four rounds in America, and he loses two of them. To add insult to injury, Ray became the first member of the team ever to lose a match before the finals. Also, he undergoes a Curb-Stomp Battle against Eddy, getting taken down 0-2.
Broken Base: Ray's match against Crusher is a subject of heavy debate among the fandom. The Ass Pull victory granted to Crusher (a rock from the stadium's remains hit his Beyblade and let it stay in the Stadium while Driger MS lost by stadium out) is either a Heartwarming Moment as his love for his sister pushed him through the battle and allowed him to win, or a cheap victory awarded to someone who really didn't deserve the victory as he did pretty poorly against Ray, who dominated for the majority of the fight.
Macekre: Nelvana, already known for sterilizing another popular anime series, more or less did a 4Kids-level job with Beyblade, ranging from changing and Americanising many of the character names (despite the obvious Japanese setting), to changing plotlines and plot points, and adding completely unnecessary and annoying characters, such as Dizzi and the two commentators that talk over every battle. They also used the same opening theme for all three series (said opening themeis actually popular, though).
Hillary gets this reaction due to being a girl who was created just so the Bladebreakers could have some female presence. The problem is that she wasn't a blader, which really ground some people's gears. The writers had no idea what to do with her besides making her the "token girl", so she pretty much just became moving background in the third season. She never lives up to the full potential of The Chick (namely, being The Heart).
Daichi (for perceived stealing of the spotlight from the rest of the cast).
Ming Ming also qualifies. Her pop star status annoys most people and think she shouldn't be Beyblading. Including Daichi... until she defeated him.
Tear Jerker: Ray's battle against Bryan, with Bryan's Bit-Beast attacking both Ray's Beyblade and Ray himself. Even though the fate of the world is at stake, and the only way the Bladebreakers can get to the finals and stop Biovolt's evil plans is if Ray wins his battle, his friends are more concerned about Ray's well-being and try telling him to withdraw from the battle. However, Ray keeps refusing to listen to them, and continues to fight even though he's barely able to endure the pain as Falborg's attacks just keep getting worse as the battle goes on. Near the end, Ray's Bit-Beast Driger ends up sacrificing itself to save Ray's life by shielding him from further attacks, before destroying Bryan's Beyblade with a powerful Tiger Claw attack. Right afterwards, everyone is excited when the light from that final Tiger Claw attack has cleared up and they realize that Ray has won the battle, but their excitement quickly fades when they notice Ray's unconscious body on the stadium floor.
They Changed It, Now It Sucks: Subverted as some fans initially disliked the new animation style featured in the second season as well as the subtle changes in personality the characters exhibited (e.g. Tyson losing all his character development) but on the other hand many believe that the second season's story arc was much less formulaic and overall more interesting as well as the fact that the more detailed bit-beast design and the Conspicuous CGI for the beyblades was a nice touch.
Villain Sue: Brooklyn, oh man, Brooklyn! The guy has so much God-given natural ability at Beyblading that he never needs to practice. He even casually humiliated Kai, who ever since he first premiered has been known as one of the best in the world. He can even see visions of the future that tell him how a match will play out. And when he actually is serious, his Bit-Beast starts distorting space and warping reality. No real explanation is given for why he is so godly.
Woolseyism: On the other hand, some fans take the opposite view of the above Macekre as the English dub's overall quality isn't too bad in terms of acting especially for a merchandise driven show. Not to mention the editing was nowhere as bad as 4kids nor where the puns all over the place only cropping up from time to time. The fact that they bothered to add in Dizzi as well as all those Cgi parts does in fact show the creators put some effort and creativity in their adaptation and even the US soundtrack has some pretty kickass themes.