Chief Delphi

Any type of LEDs, technically, are legal. It's up to your team how far you want to go with it. Yes, LEDs are fun (I should know) Yes, they will make you more noticeable on the field, and they make your robot more exciting for the general public. However, you have to know the ins and outs of lights before you start working with them.

Power consumption: You have to calculate how much power your lights will draw. Too many lights can cause your batteries to drain quickly, resulting in reduced performance in-match. Before going wild with lights like my team did last year, we made certain that all those lights would be within our power budget. It's usually pretty easy to calculate the consumption of your lights, since many manufacturers specify the current draw of their strips by the meter.
Control: If you want to do RGBLEDs, you have to know how they are controlled. There are two typed of RGB strips, classified as analog and digital. Analog strips can only show one color, across the whole strip. This type is the cheapest, and often comes with an IR controller. You can't use this controller on the robot, you'd have to design one that runs through the robot control system. Digital strips can do patterns and the like, but they are significantly more complicated to control. They typically are controlled with an arduino or RP, and can require custom code libraries.
Gameplay: If your lights are too disruptive or too bright, you might get penalties as a result of your lights. You don't want your lights blinding the drivers, as there is a rule about this, and if they are "disruptive" in any way, some pickier referees might call you out.