Seesaw

Seesaws are a type of platform objects that appear in many Mario games, and usually tilt left or right depending on where the player and/or enemies walk on it.

New Super Mario Bros. U / New Super Luigi U / New Super Mario Bros. U Deluxe
Seesaws appear in New Super Mario Bros. U as a type of platform appearing in the level Seesaw Bridge. They also appear in the New Super Luigi U level, Sumo Bro Bridge. Seesaws reappear in both levels in the Nintendo Switch port, New Super Mario Bros. U Deluxe.

A similar type of seesaw, the Seesaw Shroom, appears in all 3 games as a type of Mushroom Platform.

Super Mario Maker 2
Seesaws appear as a course element in Super Mario Maker 2. They appear as orange platforms in the Super Mario World style, and red in all other styles, and retain most of their characteristics from previous appearances. In the Super Mario Bros., Super Mario Bros. 3, and Super Mario World styles, they appear to be metallic, but in the New Super Mario Bros. U style, they are wooden. Like normal Lifts, their length can be changed, and they can be placed on tracks.

Seesaws can be abruptly tilted when a Thwomp falls on one side, throwing any playable characters and objects on the other side high into the air. This can also be achieved if a player Ground Pounds on the Seesaw (requiring a Dry Bones Shell or big Goomba's Shoe to do so in the Super Mario Bros. and Super Mario Bros. 3 styles). Furthermore, Bowser can perform this as well in the Super Mario Bros. 3 style using his Ground Pound attack.

Course elements have different weights. Twisters weigh nothing, while Spiny Shells, Buzzy Shells, Dry Bones Shells, Beach Koopas, and Koopa Shells weigh half a normal object. All players, regardless of their power-ups, weigh the same. Munchers, Thwomps, Wigglers, Bill Blasters, Cannons, Goomba's Shoes, Boom Boom, Bowser Jr., Bowser, Big Mushrooms, 10-Coins, and their variants weigh double. In addition, applying the Super Mushroom modifier to a course element doubles its weight.

Super Mario Maker 2

 * North American website bio: "These are perfect for risky, tilt-centric courses."