Dr. Mario does an out-stretched arm spin and ends it with a stronger hit via an open-body bash. Dr. Mario is able to hover in the air when using this attack by repeatedly tapping the B Button. The move can gather vertical height once between landings if it is used and mashed while ascending (at the start of a double jump, for instance).
Dr. Tornado has the same effect as Mario Tornado, except that it is slightly stronger in terms of damage, has a lighter pull (and thus is able to rack up more hits if spaced properly), covers marginally less recovery distance, and the final attack sends opponents flying horizontally rather than vertically. Additionally, Dr. Mario doesn't yell "Yahoo!" or "Yee-haw!" when performing the attack, unlike Mario. In SSB4 and Ultimate, he will simply make a quiet grunt, identical to the one Mario uses for F.L.U.D.D. In Melee, the move has transcendent priority on all but the last hit.
In Smash 4, Dr. Tornado deals less damage but has more knockback on the last hit, capable of KOing more easily at high percents. It is also harder to break out of and has a much longer duration, while also having more range at startup. It has slightly more startup than before but is noticeably easier to mash, making it easier to use for recovery. It has more horizontal recovery distance but has significantly less vertical distance. It now also has transcendent priority on the last hit, but not on the looping hits.
In Ultimate, Dr. Tornado now hits seven times instead of five, and deals increased damage and knockback, making the move infamous for reliably KOing at significantly earlier percentages off-stage (the move is a kill confirm out of down throw akin to Luigi's variant). Additionally, Dr. Mario now gets percentage-based heavy armor during the move's startup, and the move is better for recovery as it gives him increased vertical distance and has decreased ending lag.
Special Move customization was added in Super Smash Bros. 4. These are the variations: