Nerf Yoshi's Flight
This patch changes Yoshi's flight ability in two ways. It limits the maximum height at which the player can fly and it makes Yoshi swallow shells much more quickly if they give him wings. This applies to all blue shells, as well as all shells eaten by a blue Yoshi. It somewhat resembles another existing patch but it accomplishes the effect in a much different way.
This patch creates a new type of P-Switch whose color is controlled by the On/Off switch, as seen in the pyramid level of Mario's Final World. The custom P-Switch also gets a different sprite tile. Since the patch was originally made for private use, it's not as user-friendly as it could be, but it can still be useful.
The advantage of using a patch instead of a custom sprite is that, when combined with the hex edit at
$02AC18, you can carry the custom P-Switches into another sublevel. This wouldn't be as easy to accomplish with a custom sprite.