A good rival can spur any anime character to new heights of power and greatness, and in the world of Naruto, there are more than a few rivalries around. Naruto and Sasuke constantly tried to outdo each other, and Rock Lee saw Neji Hyuga as his greatest rival to overcome. Meanwhile, Sakura Haruno had Ino Yamanaka as her own rival, mainly in their younger years.
As trainee ninja, both girls sought the approval and admiration of Sasuke Uchiha, the dreamboat, and what is more, Ino helped shake Sakura out of her self-pity and taught her that all flower buds are destined to bloom someday. The young Sakura took this to heart, and she swore to never lose to Ino again. This was a good rivalry, but after a point in Naruto, Sakura needed a few new rivals to keep her going. Who should she choose out of the entire world of anime?
10 Hinata Hyuga, The Taijutsu Powerhouse
Although Hinata Hyuga wasn't at the top of the taijutsu rankings in Naruto, she surprised everyone, most of all herself, with her incredible growth after Naruto gave her a few encouraging words during the chunin exams. Hinata had a gentle heart, and she learned to back it up with ferocious, Hyuga-style taijutsu.
Now, Hinata is a proper Hyuga clan ninja, fighting alongside her gifted cousin Neji as an equal. Sakura Haruno is also a taijutsu specialist, so both kunoichi could compete to see who can master martial arts the fastest, and they are both good-natured people who understand each other well.
9 Rukia Kuchiki, Ichigo's Supernatural Friend (Bleach)
Rukia Kuchiki is a Soul Reaper, and she played a loosely similar role in this anime as Sakura did in Naruto. Rukia is tough but fair, and quite smart too, easily complementing and supporting the male lead (Ichigo Kurosaki). Rukia is there to help keep Ichigo in line, and she can teach him a thing or two along the way.
On a personal level, Rukia and Sakura would connect well, and they have a roughly similar level of power and technique as well. They would both have great fun pushing themselves to the next level in a fierce but friendly rivalry.
8 Eijiro Kirishima, The Armored Hero (My Hero Academia)
The trainee hero named Eijiro Kirishima has more in common with Sakura than either character would expect. Both of them are fierce melee fighters who struggled at first with self-doubt about their own capabilities, and in that sense, they would certainly become good friends and eternal rivals.
Eijiro doubted his Hardening Quirk at first, thinking it was too defensive and too boring for hero work. But after he saw Mina Ashido bravely face a villain, he resolved to believe in himself and end his self-pity. Now he can prove his worth to Sakura, and vice versa.
7 Lisanna Strauss, The Animal Mimic (Fairy Tail)
Lisanna Strauss is the youngest of the three Strausses, and arguably the least powerful of them. Like Elfman and Mirajane Strauss, Lisanna can partially morph into animals, often to grow bird wings and talons. She can also assume a cat-girl form for agile melee combat, complete with claws and ears.
Like Sakura, Lisanna is a tough and determined fighter with everything to prove, and she has plenty of friends and teammates to set a good example for her. She and Sakura would understand each other, and they could form an intense rivalry to see which flower bud can bloom first.
6 Koichi Hirose, The Morioh Town Sidekick (JoJo's Bizarre Adventure)
Koichi Hirose is one of Josuke Higashikata's JoBros, along with Okuyasu Nijimura. At first, Koichi was little more than a bystander during Josuke's Stand battles, but then he awoke his own Stand, named Echoes, and began to use its creative powers in combat and watch Josuke's back.
Koichi is late to the party, but he's working hard to catch up, and that puts him in a similar position as Sakura early in Naruto. The two of them are clever and earnest teammates, and a rivalry could soon follow.
5 Bolin, The Pro Bender (The Legend Of Korra)
Bolin knows what it's like to play second fiddle to someone. His big brother, the Firebender named Mako, looked out for the two of them and took charge of their pro bending team, the Fire Ferrets. Before she became a powerhouse kunoichi, Sakura lagged behind Naruto and Sasuke, a position Bolin would understand to a degree.
Bolin worked hard to catch up, just like Sakura did, and the two of them could race each other to see who's the strongest brute-force fighter around. Sakura doesn't use earth chakra, but her mighty fists have a similar impact as Bolin's earthbending strikes, so it's close enough. This could be a fun, friendly rivalry.
4 Ban, The Immortal Sin (The Seven Deadly Sins)
The fox sin of greed is Ban, a martial artist who has a special secret: he cannot be killed. Some time ago, Ban drank from the fountain of immortality, thanks to his new friend Elaine, and he can rapidly regenerate even life-threatening injuries in combat.
In the original story, Ban was a friendly rival to Meliodas, the dragon sin of wrath, but really, Ban would happily compete with any ferocious fighter who can challenge him in melee combat, and Sakura, with her mighty fists and healing jutsu, could certainly keep up. Let the rivalry begin.
3 Tamaki Kotatsu, The Feline Fire Soldier (Fire Force)
For a time, Tamaki Kotatsu lagged behind her fellow fire soldiers, with the likes of Shinra Kusakabe, Arthur Boyle, and Maki Oze showing her up time and again. Tamaki hardened her resolve later on, and started training hard to catch up and prove what she can really do.
Like many of Sakura's potential rivals, Tamaki can sympathize with Sakura Haruno's position early in Naruto, and both characters are fierce and protective melee experts who are eager to show the world what they can really do. In terms of combat skills and personality alike, Sakura and Tamaki would get along great.
2 Itsuka Kendo, Class 1-B's Rep (My Hero Academia)
Eijiro Kirishima isn't the only U.A. student who could compete with Sakura Haruno on the training field. There's also Itsuka Kendo, the rep of class 1-B, and she and Sakura are almost like sisters. Both of them are tough and responsible for their age, and they know how to keep their rowdy teammates in line.
It also helps that Itsuka is a dedicated melee fighter, just like Sakura and many of Sakura's potential rivals, and Itsuka still has room to grow and improve. She and Sakura would become close friends as they compete to see who can become a true ninja or hero first.
1 Tajiro Kamado, The Kind Swordsman (Demon Slayer)
Tanjiro Kamado is always up for a good challenge, and he is far from complacent as a rookie demon slayer. Tanjiro worked diligently to train with the sword and even practice his breathing, and like her teammate Naruto, Sakura would know a thing or two about nose-to-the-grindstone training.
What is more, Tanjiro is a patient, kind fellow who sees the best in everything, and his warm, mature personality would definitely impress Sakura and prompt her to begin training with him as a partner. They could learn much from each other.