One potential new ally could be a powerful pirate from the past. For instance, a pirate who was known for his great navigation skills. Luffy could use his help to explore uncharted seas more easily.
There might be a time - displaced character who has no connection to the normal pirate world but has unique powers. Luffy, being the friendly and inclusive captain he is, would welcome this character into the crew, and together they would face new adventures.
A character from the future could also be an ally. Maybe a person with advanced technology that can help the Straw Hat crew in battles. For example, some kind of energy shield device that protects the ship from powerful attacks.
Leon Kennedy could also be an ally. He has his own set of skills and experiences in dealing with dangerous situations. In a time - travel scenario, Leon might be able to provide different perspectives and resources. For example, if Chris travels to a time where Leon has already been, Leon could give him valuable information about the local threats and how to deal with them.
When Madara travels through time, he might find allies in unexpected places. For instance, some of the minor ninja clans that were oppressed by the larger clans in the past could see Madara as a liberator if he offers them a better future. On the other hand, those who benefit from the current ninja world order, such as the Daimyo or certain powerful shinobi from other villages, might see Madara as a threat and become his enemies.
Perhaps a wise old hermit. This character could live on an island that Luffy lands on during the time skip. The hermit has knowledge of the Void Century and can give Luffy some crucial hints about the true nature of the One Piece and the history of the world. His wisdom could also help Luffy grow as a leader.
Aang could be an ally. Since Aang was the previous avatar, he could guide Naruto in understanding the avatar state and how to use it effectively. Katara could also be an ally. She could teach Naruto water - bending techniques and help him with his emotional side as she's very empathetic.
Maybe Kurama, the nine - tailed fox inside Naruto, could be an unexpected ally in a new way. Since they have a bond, Kurama could provide Naruto with extra power and insights when dealing with time - related challenges. For example, Kurama might have some ancient knowledge about the flow of time that could help Naruto in his time - patrolling duties.
In Adventure Time fanfiction, the Ice Princess could find allies in many characters. Lady Rainicorn could be one. Her flying abilities and combat skills could be very useful for the Ice Princess. BMO could also be an unexpected ally. BMO might have some knowledge or technology that could assist the Ice Princess in her adventure. Additionally, Flame Princess could be an ally under certain circumstances. If there is a threat that endangers both the Ice Kingdom and the Fire Kingdom, they could put aside their differences and work together.
There could be some of Dragon's comrades in the revolutionary army who become important figures in Luffy's upbringing. For example, a veteran revolutionary who teaches Luffy about the history of the world and the wrongdoings of the World Government.
One potential new member could be a skilled archer from a forest - dwelling tribe. They have amazing accuracy and can use special arrows made from rare materials found only in their forest. Another could be a mermaid or merman with the ability to control water in unique ways, not just for combat but also for things like navigation and finding hidden treasures.
His first potential ally could be the Lich. Since the Lich is all about destruction and chaos, just like Evil Finn in his evil state, they might team up. The Lich could provide some dark magic knowledge to Evil Finn to make him even more powerful.
The Fire Kingdom's Flame Princess could be an ally too. Her mastery over fire could complement Finn's powers in combat situations. Also, the various magical creatures in Ooo, like the gnomes or the fairies, could band together and support Finn. They might have their own ancient knowledge or magic that could be useful to Finn in his adventures with his godlike powers. Finn's kindness towards them in the past might make them more inclined to help him out.