Enemy Course

Enemy Courses (also known as World Obstacles or Enemy Battles ) are a type of battle course found in Super Mario Bros. 3, New Super Mario Bros. Wii, and New Super Mario Bros. U. Enemy Battles in Super Mario 3D World work in a similar fashion to Enemy Courses.

Super Mario Bros. 3
Each of the first six worlds of Super Mario Bros. 3 features at least one Enemy Course. An enemy will patrol the world map, moving when the player dies or clears a level, and the player must fight it if they cross paths. Depending on where they meet, the arena and any block contents may change (ex.: meeting on a water tile in World 3 will have the ground submerged underwater). If the player wins this battle, they will be rewarded with an item, such as a Starman or Music Box. In this game, Enemy Courses consist solely of Hammer Brothers and their variants. These courses can be skipped if the player uses a Music Box, which puts them to sleep until the player clears a level and/or dies twice.

If the tens digit of the player's score and both digits of their coin count match upon clearing a level (zero does not count) in Grass Land, Water Land, Sky Land, or Ice Land, a Hammer Brother Enemy Course will become a Treasure Ship (the prize for clearing the ship remains the same).

In the GBA version, once every level is beaten, the Enemy Courses can be replayed indefinitely, and the player is not forced to enter them, though they will also move if the player visits a Toad House or Spade Panel.

Similar, but immobile courses also appear in the later worlds of the game, being 1,  2,  1,, , , and  2. Of them, only the Piranha Plants can be passed with a Music Box.

New Super Mario Bros. Wii
An Enemy Course is found in all worlds except for World 9 in New Super Mario Bros. Wii. The player needs to collect eight Toad balloons, while enemies attack them, to release a chest that contains a Toad in it. Once all balloons are collected, the Toad thanks the player for rescuing him and will give the player three Super Mushrooms. These courses are played at designated areas of the Map where an enemy is found; they move when players do. In Worlds 6 and 8, the player can do their Enemy Course infinite times. The enemies do not need to be defeated, and are automatically defeated when the game is won. The players cannot quit these courses, so in order to get back to the World Map the player has to complete the course or lose a life. However, if the player loses a life, they will be knocked back to the space where they were before on the World Map.

Losing a life in any level will cause enemies to reappear on the map. Using a Star when on the map and running into one of the enemies will immediately defeat them without having to enter these courses, but the player will not receive three Super Mushrooms for doing so.

New Super Mario Bros. U / New Super Luigi U / New Super Mario Bros. U Deluxe
After being absent in New Super Mario Bros. 2, Enemy Courses return in New Super Mario Bros. U, New Super Luigi U, and New Super Mario Bros. U Deluxe; there are seven Enemy Courses this time around. As with the courses in Super Mario Bros. 3, the enemies must be defeated in order to retrieve the prize, which is a Super Star this time around, instead of three Super Mushrooms given by Toad, but if the player does not open the chest for 30 to 45 seconds, Nabbit will jump out of nowhere and steal the chest's contents. (If a player is playing as Nabbit in New Super Luigi U or either game of the port, the screen simply fades to black.) In New Super Luigi U, the prize is either a Propeller Mushroom, a Mini Mushroom, or a Penguin Suit. If the enemy cannot be defeated by normal stomps, such as Boos, a Flying ? Block holding a Super Star floats by for Mario and co. to use. Upon clearing an Enemy Course in New Super Mario Bros. U Deluxe, the player may receive a Super Crown in either base game, as well as the rewards from New Super Luigi U no longer being exclusive to that game in the port.

Trivia

 * In New Super Mario Bros. Wii, Spinies are the only enemies that appear in Enemy Courses not to be seen on the world map.
 * An oversight in Super Mario Bros. 3 may randomly cause an Enemy Course to overlap with an N-Mark Spade Panel on the overworld maps that Enemy Courses appear in, causing them to combine and move around indefinitely, thus causing a softlock.