When it comes to Bleach, they have a fairly good track record with the heroes not always coming out on top. Ichigo had to fight his more prominent enemies at least twice, sometimes even three times before getting a leg up on them. It goes beyond just him as well, the Gotei 13 taking their fair share of losses.
That's left open quite a few situations where it felt like the hero was going to come out on top, only to fail in the end. Some of these losses were just minor setbacks, while others led to a better story being told in the end.
10 Byakuya vs Renji
On the surface, Byakuya seemed like an opponent that Ichigo was destined to defeat, but as more of Renji's backstory came to light, it felt like he had a chance to best his captain in combat.
Renji's character arc in general during the Soul Society arc was really well done, his will to protect Rukia growing and growing, causing him to fight Byakuya with everything he had. The ensuing fight was very well done, but Renji was proven to be inferior to the elder Kuchiki.
9 Grimmjow vs Ichigo
In the end, Ichigo ended up getting the win here, but it took a round three before we got there. In round two, everything pointed to Ichigo picking up a W, Grimm only had one arm for god's sake, but the fight was cut short, ending in a draw.
Grimm was ready to release, Ulquiorra stepping in to stop him. The fight itself felt like more of a skirmish, a means of showing Ichigo's progress while teasing what was to come in their final confrontation.
8 Aizen Vs The World
Everyone knew Ichigo was going to be the one to take down Aizen, the villain being built up as the big bad throughout the whole series. So in that sense, it wasn't so much a surprise that he walked away from this encounter alive.
It's still surprising the ease that he was able to handle what felt like the entire Gotei 13, pulling one of the ultimate troll moves by having Hitsugaya think he'd impaled him when reality it was Momo.
7 As Nodt vs Byakuya
Byakuya had been established as one of the stronger captains in the Gotei 13, as well as one of the smartest and most patient fighters they had. When the Quincy's made their first attack on Soul Society, he was the last guy you'd expect to lose, especially as handily as he did.
It's what made the fight so effective, establishing both the Quincy's and As Nodt as forces to be reckoned with. It was made even better when As Nodt's defeat came at Rukia's hands later.
6 Quilge vs Ichigo
This is a fight Ichigo failed to win more by technicality as he was the superior fighter throughout the majority of the fight due to his Banaki being unstealable. Quilge was on the ropes when Urahara struck him from behind, forcing him to use his unique ability to jail Ichigo, thinking he could deal with the others.
He was proven wrong before he even got a chance, being cut clean in half by a returning Grimmjow. It was a rather lackluster display considering how dominant As Nodt and others looked in Soul Society.
5 Mask vs. Kensei and Rose
This fight was one of the first that started a trend throughout this arc, where Kubo was just attempting to show off all of the Bankai's and Shikai people had with little regard to the story any longer.
Both Rose and Kensai got to show off what they could do, pushing Mask to the point where he used his letter's power before being handled pretty easily. If it weren't for the Royal Guard, the Visored would be the most disrespected characters in the whole series.
4 Elite Guard vs. Royal Guard
For all the good that came of the Quincy war, the fight revolving around the Royal Guard is one of the worst. This fight should have been a showcase of their talents, leading to Ywach and Jugram having to take the guard down themselves.
Instead, the only Royal Guard that got to show off their talents in full was Ichibei. The rest were dispatched like they were mere fodder and not the supposed elite of the elite they were made out to be during the series. Everything about this fight was so underwhelming.
3 Lille Vs Shunsui
The Elite Guard was far too overpowered as characters, taking multiple captains to take them down due to their ridiculous abilities, and Lillie having multiple forms to his Vollstandig for some reason.
Them being this way could be forgiven if characters like Shunsui weren't thrown by the waste side to prop these Sternritters up. Admittedly, it did lead to an awesome moment with Shunsui and Nanao, where she received her real Zanpakuto. It's still a shame that Shunsui couldn't handle him on his own.
2 Gerard vs The World
With Aizen, him taking on an ungodly amount of opponents could at least be explained and led to a satisfying fight with Ichigo down the line, but Gerard? Everything about this fight felt like a waste of time that was only meant to maximize the amount of Bankai's we got to see from characters.
The fact Kenpachi finally achieve his full power level and still didn't take down this Thor wannabe is a travesty. Gerard epitomized the feet-dragging that Kubo did towards the tail end of this final arc.
1 Yhwach vs Ichigo
Everything seemed to be leading up to this second fight with Yhwach, where Ichigo could save the day, and the arc would reach its end. That was far from what happened, despite Ichigo having a badass looking transformation, Yhwach was unharmed by the end of it.
Not only that, but he also stole Ichigo's power, performed another Auswhalen, becoming even more powerful than he was before. It did lead to a confrontation with Aizen like a chapter or two later (along with a third Ichigo fight), but this fight felt overextended.