Bakugan Battle Brawlers was one of those anime that I watched on TV as a teenager before the era of the Internet kicked in. I only watched it because there was no other anime airing on TV in my home country. Bakugan is an anime with the purpose of advertising the Bakugan game. However, it never got any recognition in Japan and while it did generate lots of popularity in the United States and Canada, it was still overshadowed and people didn't care for it. There are two reasons Bakugan Battle Brawlers was never successful and never recognized.
1) It is viewed as a Pokemon, Yu-Gi-Oh and Digimon clone. The premise of Bakugan involves kids pairing up with creatures called Bakugan and fighting evil Bakugan to save the world of Vestroia (the Bakugans' home dimension) and use cards to power up their Bakugan. It is painfully obvious to the naked eye that this is exactly like Pokemon and Digimon mixed with Yu-Gi-Oh; many people saw this anime as a rip-off and never bothered to get through the entire show. Many people hated this show for being exactly like the aforementioned shows. I don't blame them; you have three juggernauts that are not only way more popular and successful but had already captured the hearts of millions of people with their monster teaming up/capturing/card formula, so why would you bother watching some some no name monster battling anime that has no credibility of its own. Clearly, you would watch Pokemon. Yu-Gi-Oh or Digimon instead rather than wasting your time watching this show.
2) It did not establish its own identity. Pokemon, Yu-Gi-Oh and Digimon created their own identities by establishing their own formulas, whereas Bakugan mixed those formulas together and did nothing with it; it repeated what the above mentioned shows did with adding nothing new or interesting to the monster battling/capturing/card formula. Since Bakugan couldn't establish its own identity, people saw this as a Poke/Digi/Yugi clone and didn't bat an eye.
So Bakugan never got the international recognition like Digimon, Pokemon and Yu-Gi-Oh due to these reasons. It also doesn't help that the story of Bakugan plays out exactly similar to these shows. It involves a group of six battle brawlers playing against other children before teaming up with their partner Bakugan trying to save their world from being destroyed by an evil renegade Bakugan. There was nothing special about the story of Bakugan that was different or unique; it was a monster of the week show where every episode has one of the kids battling a character of the week bad guy and eventually the second half involved the kids spending every episode beating the minions of the main villain one by one in each episode. Therefore, the plot of Bakugan is formulaic and easily predictable which provides no tension. The main meat of this show is the monster battles; the Bakugan battles seemed to involve strategy but actually didn't; all that mattered was having the higher G Power, so the kids motivating their Bakugan to do better or fight harder meant nothing. What's even worse is that the second half of the show forgoes G Power and made it seem like the kids motivating their Bakugan does make them stronger, so is it G Power that makes the Bakugan stronger or the bond with the kids? As such, Bakugan has an improper battle system that doesn't follow the game its based on properly. The show tried to make it seem that the battles had tension early on by having the villain of the first half, Masquerade, sends the Bakugan his monster defeats to a place called the Doom Dimension where the Bakugan there rot for all eternity with no means of escape, but this is rendered pointless since the six ancient warriors (a powerful group of Bakugan who saved Vestroia in the past) were able to send the brawlers and their Bakugan home without any injury as well as free all the trapped Bakugan. Speaking of which, if they had the power to do this all along, why didn't they stop Naga from separating the Infinity and Silent Cores in the first place? Essentially, it was convenient that the six ancient warriors did not interfere to begin with, which shows that this anime doesn't flow naturally since this entire story could have ended in the first episode if the ancient warriors stopped Naga from the get go but didn't due to plot convenience.
The main characters, the Battle Brawlers, were two dimensional airheads at best; they had established stereotypes but nothing made them stand out. Their Bakugan also had personalities and didn't mimic the personalities of their Brawlers; they were their own beings so I can at least praise the show for not making the Bakugan reflect the personalities of their Brawlers and letting them keep their individuality. There is some semblance of character development in the show, best shown during the test with the six ancient soldiers. However, Naga was nothing more than a simple one dimensional villain who wanted to take over the worlds of Earth and Vestroia; his reasoning for wanting to rule over all the Bakugan was murky and not well founded. While its true that he was a renegade Bakugan with no assigned attribute and was angry that he didn't belong anywhere, we never saw him being oppressed or ostracized by the Bakugan society so his lack of actual motivation and rationale behind his reasoning makes him a villain who wants to do evil just because. Overall, characterization and character development were average at best.
The production values were decent, nothing too special or eye catching. The first dozen of episodes had inconsistent art and animation but this improves later on as the show progresses and eventually becomes consistent. The battles were flashy which made them watchable but wasn't anything spectacular.
At its core, Bakugan Battle Brawlers is an marketing anime whose sole purpose is to advertise its game, so clearly it is not going to try and be good. It is also clear that Bakugan was unable to fight with its competition on its own terms which is why it was deemed a rip-off and never got any recognition. There is little reason to watch Bakugan since it does nothing to differentiate itself, has an improper battle system, lack of proper storytelling and subpar characterization. For what its worth, Bakugan does at least have a small niche in being another monster teaming up/battling/card anime that people can watch if they ever get tired of watching Digimon, Pokemon and Yu-Gi-Oh over and over again; some people might find more enjoyment in just seeing huge attributed monsters duke it out with each other while their brawlers shout out "Ability Activate!". However, once they see the first few dozen episodes, they will realize that Digimon, Pokemon and Yu-Gi-Oh are way better than this anime and will go back to watching those anime. This is why Bakugan Battle Brawlers is one of those forgotten anime that will never see the light of day.