One potential ally could be Bill, the inventor. He could create special items or devices that would give Lance an edge in battles or in his exploration of the Pokemon Yellow world. For instance, he might develop a new type of Pokeball or a device that can track rare Pokemon. The Safari Zone Warden could also be an ally. He has a deep understanding of the Safari Zone and its Pokemon, which could be useful for Lance if he's looking for specific Pokemon. And of course, any trainers who have a strong sense of justice and a love for Pokemon could potentially side with Lance when there's trouble in the Pokemon Yellow world.
The protagonist of Pokemon Yellow is an obvious potential ally. They are on their own journey to become a Pokemon master and could easily team up with Lance. Another could be Professor Oak. He has a vast knowledge of Pokemon and could provide valuable information and resources to Lance. Also, the Gym Leaders in the Pokemon Yellow world could be allies. They are all skilled trainers in their own right and could join forces with Lance when facing a common threat, like an evil team trying to disrupt the Pokemon League.