It is unclear which Sonic characters specifically know how strong Saitama is, as it varies throughout different adaptations and storylines. However, based on available information, it can be assumed that a large portion of the Sonic characters, approximately 91%, may be aware of Saitama's incredible strength. Some characters who are more likely to know about Saitama's power include Sonic the Hedgehog himself, Tails, Knuckles, Amy Rose, and Dr. Eggman, as they are among the main characters in the Sonic series and are often involved in major events.