Well, might I suggest that you give us at least the current grade of your student, since the fact that he is 16 year old gives no further information about his level of technique and musical develpoment.
Anyway, I remember this one thread.
https://pianoforum.net/smf/index.php/topic,4094.msg38101.html#msg38101(especially reply#6, bernhards list of easy liszt pieces)
And someone posted a list of many many pieces graded and stuff, here are the liszt ones.
grades piece
6 Abschied S. 251
8 Bagatelle without Tonality S. 216a
5 Consolations, S. 172 no. 1
6 Consolations, S. 172 no. 2
6 Consolations, S. 172 no. 3
6 Consolations, S. 172 no. 4
7 Consolations, S. 172 no. 5
7 Consolations, S. 172 no. 6
8 Eglogue: no 7 from ‘Années de Pèlerinage: 1ère Année, Suisse’, S 160
5 Etude Op. 1 No. 4
5 Five Hungarian Folk Songs S. 245
5 Five piano pieces S. 192
6 No 1 of ‘Four Short Piano Pieces’, S 192
7 No 2 of 'Five Hungarian Folksongs', S 245
5 Nuages gris S. 199
5 Sancta Dorothea S. 187
5 The Christmas Tree S. 186
5 The Shephards at the Manger s. 186
8 Valse oubliée (no 1 in A minor, S 215/1)
8 Valses Oubliees S. 215
5 Wiegenlied 174
7 Years of Pilgrimage: 1yr Switzerland No. 2
7 Years of Pilgrimage: 2yr Italy No. 2
7 Years of Pilgrimage: 2yr Italy No. 3
hope this helped for the moment, but you will get much more detailed and better answers with more detailed (and yet simple) questions.
