Hi all, how do you make this striped look of horizontal ombre lines on each tier? Is this fondant decorated or buttercream with a decorator's comb passed on the cake sides? Looking for a tutorial on youtube, google search and this site but can't get one yet. Any help or links on this is appreciated! love you all

Looks like buttercream marked with a decorator's comb to me.  I'm used to seeing the lines made by a spatula or spoon, but these are so even I think you are right on with the comb guess.

I would imagine that the cake is iced in buttercream - probably non crusting so that you have plenty of time to work with the different colours  (maybe pipe a straight edge then fill with a spatula smoothing each colour as you go?) and then as you say a comb decorating passed through it, it looks like the pattern that I achieved using a plastic baby fork, just a bit straighter (haha after an hour trying to use decorating tools I pulled the fork out of the drawer to try it and found that it gave the effect I was trying so hard to achieve) on a cake that I made for my PIL wedding anniversary.