Character appearances, traits and behaviour are the main factors which can lead to one making a comparison to another character from a completely different anime/manga series. This thread is to discuss, compare and share your finds!
C-C-C-C-C-Combo breaker!
Goku from Dragon Ball, Luffy from One Piece, Yusuke from Yu Yu Hakusho, and Oga from Beelzebub remind me of each other. All four love to fight that they don't care who they fight with or how they fight. Apart from being main characters, they all have people they're close with and will go any lengths (I think, for Oga <_<) to save their friends.
Oga's unique because he's an antihero, although he has shown he cares for Beel and Hilda. Yusuke was misunderstood, I guess, and didn't have anything to keep him happy. Plus, another major trait they share is humor. All four are pretty stupid, which adds hilariousness, but they can be pretty smart in fights, if not lucky. For example, when Goku first met Bulma, he gave her a patpat because he wondered if she had a penis, and even took off her panties. Luffy, in order to prove his toughness to his pirate friends when he was a kid, stabbed his cheek and cut it to show his toughness; when he was caught in a whirlpool, he didn't really care and was even cheerful about it. This was at the beginning, and he's still alive as of recent chapter, so that shows he survived. Yusuke's a pervert, like when in the Shinobu arc he tried to trick Botan into revealing her measurements. Oga was willing to hurt his allies to get to his enemy, like when he whacked that Ka-something out of his way since Ka-blah wanted revenge on Miki for hitting him. People thought Oga was trying to protect Ka-blah in his own way, but Oga said it's cuz he was in the way. When Toujou arrived around that chapter, he was raring to fight and asked who was gonna fight. He pointed at few people, finally at Oga, to which Oga prepared to fight. People went "NOT YOUR OWN ALLY!

" I think.
Goku and Oga get stronger in fights because they want to prove themselves. They enjoy fighting for fighting, which makes them persevere. They can find a way to beat an opponent and refuse to give up. Their desire to fight is what makes them refuse to back down and want to fight, no matter how strong the opponent is. Although Goku thought Cell had no weakness and was probably too powerful for him, he still wanted to fight it.
Luffy and Yusuke get stronger in fights for the sake of their loved ones. Even when Yusuke was close to dying against an enemy, he withstood the lightning shocks and brought out the power to kill the enemy because Keiko and Botan were in danger. He went from being unable to move from pain and fatigue to getting enough power to take out about seven of his enemies who were pretty powerful just by seeing how close Keiko and Botan were to being killed. Same with his match against Toguro: when Yusuke thought Toguro killed Kuwabara, Yusuke's power increased dramatically to the point where he could take Toguro at 100%'s strength with little to no problem (I think) when he had major trouble with the same Toguro. Luffy's the same. No matter what or how, he will try to find a way to beat his enemies to protect his comrades. To try and save Ace, Luffy kept on going even though he was poisoned and tired for his brother's sake. Even for people like Robin and Nami, he was willing to fight extremely tough opponents to save them and to make them happy. Naruto (do I really need to say the manga?) is same. He was scared shitless of Gaara at first, but when he heard Sasuke's refusal to let his comrades die before his eyes, and seeing Sakura's life in danger, Naruto got the courage and beat Gaara and saved Sakura. He nearly died and was in danger, but he never faltered.
Kurama and Kakashi are quite similar. Both are fucking awesome. Both are humorous, intelligent, and scary when they're mad/serious. Although Kurama was once a demon fox, he's awesome as Shuichi IMO. When you see Kurama/Kakashi and they're on the opposite side, you know you're fucked.
That's all I can be assed to type right now.