Obviously, Sonic himself is extremely popular. He's the main character, after all. Tails also often makes an appearance as Sonic's sidekick. Knuckles is another popular one, with his strength and connection to the Chaos Emeralds. And then there are the villains like Dr. Eggman who are frequently part of the death battle scenarios in these fanfictions.
Well, one interesting plot could be Sonic facing off against an unexpected and powerful new foe. Maybe a character from another universe who has unique powers that Sonic has to figure out how to counter during the death battle. Another could be Sonic teaming up with an unlikely ally in the fanfiction's death battle scenario.
Shadow could be a very challenging opponent. He has similar speed and abilities as Sonic, and in a death battle scenario, his more brooding and sometimes ruthless nature could give him an edge. Plus, if the Sonic watch is involved, Shadow might be more willing to use underhanded tactics to get it for himself or to stop Sonic from using it.
Well, in some fanfictions, the battle might start as a misunderstanding. Spiderman could be in Gotham chasing a bad guy who has a connection to New York and Batman mistakes him for a new threat. In this case, Spiderman would try to explain himself but Batman, being the brooding detective, might not listen. Then there are scenarios where the battle takes place in a neutral location like an abandoned warehouse. Here, both of them have to rely on their skills and resources. Spiderman would use his webs to create obstacles and Batman would use his gadgets to break through them. Also, there could be a scenario where they team up against a greater threat first and then due to a clash of egos, they end up fighting each other.
In a 'Naruto vs Ichigo' death battle fanfic, there are several important factors. Naruto's chakra control and his ability to learn new jutsu quickly are important. He can also use nature transformation, which can give him an edge against different opponents. Ichigo's spiritual pressure is a major factor. The more he can control and increase it, the more powerful he becomes. Also, his ability to sense and react to his opponent's attacks is crucial. Another factor is their experience in battle. Both have faced many tough opponents in their series, and that experience will play a role in how they fight each other.
Well, it's really hard to say for sure. Naruto has his amazing ninjutsu and the power of the Nine - Tails. Ichigo, on the other hand, has his Soul Reaper powers. But if I had to pick, I'd say Ichigo. His Bankai and Hollow powers give him a huge edge in terms of raw power and speed.
In the 'naruto vs ichigo death battle reaction fanfiction', reactions can be quite diverse. For Naruto fans, they might cheer when he uses his Rasengan in a creative way against Ichigo. Ichigo fans, on the other hand, would likely react strongly when he unsheathes his Zanpakuto and shows off its special abilities. There could also be a sense of disappointment from fans if their favorite character is losing or not performing as expected.
One idea could be Sonic facing off against a powerful new villain in a time - based battle. The watch could play a role in controlling time during the fight. Another plot could involve Sonic teaming up with other characters from his universe because of a threat revealed through the Death Battle fanfiction concept. Maybe the watch has some special powers that are misused by an enemy, leading to a chaotic situation that Sonic has to fix.
One common plot twist is when the powers of Naruto and Ichigo somehow merge during the battle, creating a whole new set of abilities that neither of them expected. This can change the entire dynamic of the fight.