They changed the dunk types this yr. On camera relative control (default) pushing stick towards the hoop is the normal/signature dunks, up or to the left of the hoop is hopstep dunks, down or to the right of the hoop is rim hang dunks....generally more powerful looking dunks, and away from the hoop is reverse dunks on fast breaks or a spin dunk in traffic.
U can also choose to do do left handed hop step lay-ups, right handed hop step layups, reverse layups (ala jordan, kobe, and more athletic players in the league), and euro step layups while u hold left trigger while going towards the hoops. U can also do different layups without holding the left trigger.
The Wade dunk you talk about is part of the hopstep dunks that are mapped to the right stick