Hmmm
G Revolution: If you aren't the Bladebreakers or the two members blading in the World Champions, you're not getting much to do (outside of Mariah, props for beating Ray and Max at the same time while waiting for Kai and Tyson).
Metal Fusion: I actually like Kenta since despite his losses, he got good character development, Benkei was good, didn't even hate the english voice acting...okay got it, Hikaru's arc got dropped, Hyoma got overshadowed too quickly, Teru's performance against Ryutaro was lackluster, Sora didn't get to do anything following his second episode (love him to death though), and Busajima could've played a much bigger role. Guess the Kuma's were throwaway.
Metal Masters: Outside of Team Louviska, Yu never got that awesome one v one cool battle compared to the rest of Gan Gan Galaxy, Lovushka could've been a "bit " more threathening (wish Lera got to battle), and Ziggurat went down too easily against Zeo...just like Anton.
Fury: Benkei got dropped, the Nemesis bladers needed a bit more personality, Jack got KOed, no word on Damien, the shorter season really hampered the focus some people needed, Yuki's arc about standing up for himself didn't go the distance (but in his fairness, his goal is uniting the Legendary Bladers so team battles make the most sense)
Zero-G: If you're a water blader, you suck. At least Kite beat Karura. Oh yeah, Akuya was a bit disappointing...I didn't hate Zero G.
Burst: Rantaro (well he won his final battle in the team tournament)and Daina didn't get to do much after the team tournament since they didn't qualify, Wakiya really needed a tough win in the second half of the series, having the team tournament be a best of five (or giving them alternate bey avatars) would've helped legitmatize most of the other teams, heard Yugo's more consist in the manga, wanted a bit more Orochi (I love him too much lol), Naoki could've done more, etc.
Burst God: Rantaro stopped getting any chance to beyblade after the prelims of the World League until they got to the finals (at least he also won his final battle outside of Kurtz). The other main characters, even Cuza got development, Trad in the first half wasn't the greatest. They could've dived into the Snake Pit lore a bit more or at least give Silver Eye something to do. Would've loved to see more bladers undergo the Requiem Project. Hating Stan is kind of a meme at this point but he got his just desserts when Rickson beat him. And they cut some of the God Bladers Cup battles too short, Lui vs Xhakas' been a freaking dream. Plus Ken and Zac got next to NOTHING TO DO...arghh. I still love this season.
Burst Cho-Z: Houi got dropped too early especially since he was close to beating Valt too, Fubuki and Suoh's arc ended well but they didn't get much to do in the second half: would've loved to get more on Suoh's fixation and history with beating Lui. Lui should've came back (at least he was good for what we got of him). I actually have no problems with any of the Z4 or Kitt/Free/Shu tho, all of them got some character development (feel Free...I'm not funny, to disagree). While I like the Rebel Bey Club and Beigoma club war, the rivalry could've went a bit deeper. Kyle really could've done more, Evel went MIA after 41, and wish they could've played on Night being related to Zac. Still like this season enough.
GT: Well this is gonna be a hot take. Amane just needs a valid win or get the Gold Turbo, and he might get one pretty soon. Not too worried about Blind, win or lose, he just wants to draw out the strength of his opponent and see them shine and I don't mind if he loses. Joe coming back would be cool, but he had such a strong run for the time that we got him. Lodin definitely should: he's taking "the trying beyblade as another sport to be the best" route much better than Garland or Julian ever did and I wanna know who/what convinced to since he genuinely likes it from what we've seen of him. Delta's gotten better.
Really that's all the faults I have with the beyblade seasons, but even at their worst, they're still entertaining and good enough. Even Wheelz (Raiderz can die in a ditch though).