Hydrangea petiolaris if you want a self clinger.
If you'd like roses, clematis or lonicera you'll need to attach wires to the wall in a grid type pattern for the plants to be tied to, if you don't they'll not grow upwards they'll flop down to the ground in a heap.

You will need to be guided by the orientation of the arch because certain climbers need full sun, some semi and some shade.

Have a look at Goypedia in the A-Z at the foot of the page. Click on A for arch ideas or C for climbing plants. This may give you some idea of what you like personally then you can come back and get more information about your own particulat situation. Is the arch in a north S E or W facing garden. Is it sandy or peaty etc.

got to be a wisteria!