While you are on the landmark with the 1 and 2 on it, you might notice that there is a challenge on the roof.  Go ahead and grab it, and make certain you get the Fourth Style while you are there. 

You will now be at the Fifteenth Challenge of painting some Billboards.  You will need to use the Z-pad to launch yourself, and the Thirteenth Billboard will be right there.  You then need to go around the corner to get to the next one.  Do a sticky wall climb to get to the Fourteenth Billboard. 

At some point in time in this part of the game, the Blimp comes around.  If you have paint and can smack it, then it will be colored for you.  Sweet. 

The Sixteenth Challenge is right there, so go and get it.  It involves painting some houses purple and yellow.  This can be difficult, as there is water in front of it.  There is fortunately many colors available there for it.  It is easier to do the purple ones by jumping on the roof.  That way you don’t have to deal with all the colors. By the way, there are two trees by this water, so color them for a Tree total of 13.  By the way, you should be able to get the Fifteenth Billboard and Sixteenth Billboard here. 

The Seventeenth Challenge will be waiting at the end of it.  You will need to do this race thing.  It will involve some jumping and one long sticky jump, but you will have it in the end. 

There are two challenges here nearby.  The orange arrow is another one where you are getting rid of Inkies.  Go and take them out, and that will end the Eighteenth Challenge.  You should probably paint the 6 trees in the area (4 area in a gated area) and get your Tree Total up to 19. 

As for the Nineteenth Challenge, you will have to paint a large area red.  You will have the Fifth Raydian Batch, the Sixth Raydian Batch, and the Seventh Raydian Batch for a total of 73.  Now, you may notice that your Raydian level might be a little lower or higher than that amount.  That is due to the free-roaming Raydians located on the streets that you can get later. The Fifth Style is also here, so make certain that you get that.  By the way, make sure you go a little more to the left at the end of this and pick up the Seventeenth Billboard and Eighteenth Billboard.