By saying tilesets, what you mean? You mean new tiles right?

Like custom tiles of grass, walls, dirt, water and trees right? That have been done alot of times, but most of what is used in solarus games are original zelda tiles from zelda a link to the past and minish cap.
Max made ocean heart which is all custom tiles and I make custom tiles too in paint.net that i draw myself. Like these:

Lots of games on solarus have custom tiles. If you want you can get into pixel art yourself, there are lots of good guides on youtube. I prefer to draw in paint.net, but lots use gimp for drawing.