To be honest, I can't really say I've hated many characters in any of the Beyblade Burst anime. I've hated several characters in the OG and MFB series, but for Burst... that's a hard one.
I'll list characters I simply dislike the most, but for the most part it doesn't mean I absolutely hate them. With that said, let's go...
Beyblade Burst:
- Nika Aoi - Already starting with a controversial opinion so I'll say this right now, I do not hate Nika but I just generally don't care for cheerleader-type characters since they don't do anything. It's the same reason I didn't care for Hiromi from V-Force. She does get better in Super-Z but only on the same level as Tokonatsu in the first series (FYI, Tokonatsu gets a pass because of Super-Z).
- Naoki Minamo - I don't hate him, I just think he had so much potential but he was easily forgotten and wasted. Not expecting an arc surrounding him or anything but he only lasted less than 3 episodes and was gone and never mentioned again. I know this also happened with Jin too but Jin wasn't as built up as Naoki so I gave him a pass.
Beyblade Burst God:
- Trad Vasquez - Now here's a character I truly dislike in Burst. To be honest, I can't stand him. I know a lot of people liked him for being the more realistic mentor but he was just too much of a downer (and not even in a charming way), wasn't very pleasant and was way too closed-minded, which is something he never grew out of. He's also liked to put all the blame to any faults on Valt whilst acting like Stan behaving like a brat isn't a big deal. He had a couple of sympathetic moments but he was so boring and annoying, he was like a piece of wood.
- Django Del Toro - I know people will pick Stan over Django as being the worse of the two but Django had this "build up" surrounding him when he left BC Sol and then around 20 episodes later, he's pushed away and just disappears into thin air. Stan, at least became a bit stronger when he left but Django had nothing.
- Stan Hamburg - He's one of my lesser favourite characters that I've always defended so why did I add him here? It's not because he is a jerk or a brat, it's because he never really learns his lesson which made things repetitive and is generally an idiot. I did feel sorry for him in episode 20 though.
- Honey Guten - Same reasons as to why I never cared for Nika applies with Honey, though at least she doesn't take as much screentime.
- Ruwei Sun - Of all the Big 5, he gets the least focus (and it's a noticeable difference too) which is a shame because I liked his personality. I know I bring up a lot of characters I dislike most as being out-of-focus but Ruwei is supposed to be a somewhat major character and yet, characters with smaller roles like Boa and Clio are more focused than him.
Beyblade Burst Super-Z:
- Ranjiro Kiyama - Why did we need another copy of Rantaro? I get it, he's Rantaro's brother but he's hardly different to his brother (no, being a leader of a gang doesn't count). He's just a constant test dummy like his brother, he's a bumbling idiot like his brother and only serves as the series' comic relief... like his brother. So why is he here but not Rantaro? It's because Rantaro was unique for his time and he had more character development than Ranjiro.
That's all I could think of for now. Just keep in mind that most of the ones I've listed aren't characters I strongly disliked (except for Trad) so... don't be offended lol.
Eh, I will think of something to put here...
... later ;)