Through the different Gaia Memories, Double has access to various combinations of powers, weapons, strengths, and weaknesses. Rather than having explicitly defined forms like the Phase 1 Heisei Riders, Double began the trend of mix-and-match powers, a feature shared by several other Phase 2 Heisei Riders and Reiwa Riders. Shotaro's habit of flicking his wrist carries over to Double. If their Rider form takes any significant amounts of damage, both of them will feel the pain after returning to normal and Philip will often pass out due to his weaker constitution. If their synchronization is somehow disrupted, Kamen Rider Double will be unable to move properly. Double's ability to function is dependent on the condition of both Shotaro and Philip. When Philip speaks by himself when transformed, Double's right eye flashes.

When combined as Double, Shotaro usually does most of the talking, though both speak when saying their pre-battle quote and announcing Maximum Drive attack names. Their quote at the start of a battle is 'Now, count up your sins!' ( さあ、お前の罪を数えろ！, Saa, omae no tsumi o kazoero!), a quote originally used by their predecessor and mentor, Sokichi Narumi.

When Shotaro and Philip set their Gaia Memories into the Doubledriver Belt, Philip's conscious mind enters Shotaro's body to produce Double (except when they change into FangJoker, where the opposite happens, and in Xtreme related forms, both fuse into one, due to Philip's body being stored in the Xtreme Memory).

Kamen rider w flash belt