For an integer $m{geq}3$, every integer of the form $p_m(x)$ = $frac{(m-2)x^2(m-4)x}{2}$ with x ${in}$ $mathbb{Z}$ is said to be a generalized m-gonal number. Let $a{leq}b{leq}c$ and k be positive integers. The quadruple (k, a, b, c) is said to be universal if for every nonnegative integer n there exist integers x, y, z such that n = $ap_k(x)+bp_k(y)+cp_k(z)$. Sun proved in [16] that, when k = 5 or $k{geq}7$, there are only 20 candidates for universal quadruples, which h listed explicitly and which all involve only the case of pentagonal numbers (k = 5). He veri ed that six of the candidates are in fact universal and conjectured that the remaining ones are as well. In a subsequent paper [3], Ge and Sun established universality for all but seven of the remaining candidates, leaving only (5, 1, 1, t) for t = 6, 8, 9, 10, (5, 1, 2, 8) and (5, 1, 3, s) for s = 7, 8 as candidates. In this article, we prove that the remaining seven quadruples given above are, in fact, universal.