Seen in: Legend of Zelda: Link's Awakening DX
You may seen this in the Color Dungeon of DX. This one is easy. All you have to do is to change all the red switches to blue, but here's the catch...

#1-See the black triangle? Those will change at the same time to blue. So to do this you will need four variables (I named it BlockA2, BlockB2, BlockC2 and BlockD2), create a new map, and create a new event. Now I used the Switch01 graphics for it, then put the event commands like so:

NOTE: The Conditional Branch: Variable [xxxx:BlockD2] ==1 should be ==2
#2-Ok the conditional branch will check if the other two switch is already red or blue, if not it will change it. Now copy the page and paste it in the same event:

#3-Only thing you need to change is the Event's Graphic to the color blue and the condition for it to be variable xxxx:BlockA2 to have 1 or more. Now then, create a new page and have the graphics back to the red one, then put the conditions for it to have the variable xxxxBlockA2 to have two or more and put the event Control Variable for BlockA2 to be Set to 0. This will make it reset this switch to red again (but not the other ones). Then just create anew page with the condition for the switch xxxx to be ON, just have the graphic blue and the option Through check, nothing more.
Ok now that we have the event, you will need to create another event with the same thing with some changes:

#4-Notice that the events doesn't have the same conditional branch variables and the control vairables. This is crucial for the system to work. You need to have four event with two having the same event but each one must have on the second and third page the condition with one variable (ex, Event001 will have the variable BlockA2, Event002 will have the variable BlockB2, ect.) and the first control variable in the event commands (not the ones in the conditional branch) to have the same one as the condition (BlockA2 - BlockA2).
#5-Now seperate then and copy the like this.

Now don't forget to make and event which will check if all the switches are blue, using conditional branch and to have all the four vairables with the same number (here it's the number 1).