Wii Fit Trainer (SSBU)/Back aerial
Wii Fit Trainer performs the Cobra pose, stretching her spine and striking behind her with both legs. Like her forward tilt, Wii Fit Trainer's back aerial is notorious for its immense strength relative to its extremely low startup time, coming out on frame 5. This is Wii Fit Trainer's fastest and strongest aerial attack, and is one of her most lethal kill options. All this in combination with its good coverage low to the ground (even when used while rising) causes back aerial to be considered her best out of shield option as well, although only usable when the opponent attacks from behind. The attack also covers a fairly large horizontal distance, making it somewhat useful as an approach tool when RAR'd. Due to the nature of the Cobra pose, back aerial can also be used effectively to either fade back with or cross up the opponent's shield, increasing its general safety. The late hit of back aerial has low knockback and a low launch angle, which can sometimes lead to jablock setups around mid percents if it connects as Wii Fit Trainer lands.
Despite back aerial's excellent speed and strength, it also has some major drawbacks. The first of these is the move's heavy endlag when used in the air; it is the only one of Wii Fit Trainer's aerials that cannot be autocanceled from a short hop. This makes the move fairly committal when used without landing immediately, although this issue can be somewhat remedied by Deep Breathing's fall speed increase. Secondly, the move's high knockback only comes from its sweetspot, which is small and only has a single active frame. This causes the move to sometimes be inconsistent and fail to take stocks in critical situations.