The moment problem is to determine whether a probability distribution is uniquely determined by its moments. Recently, the moment problem for random groups has been applied to the distribution of random groups, in particular the cokernels of random p-adic matrices. In this talk, we introduce the mixed moments of random groups and apply this to the joint distribution of random abelian and non-abelian groups. In the abelian case, we provide three universality results for the joint distribution of the multiple cokernels for random p-adic matrices. In the non-abelian case, we compute the joint distribution of random groups given by the quotients of the free profinite group by random relations. We also explain the universality of the cokernel of random Hermitian matrices over the ring of integers of a quadratic extension of Q_p, which is an analogue of the universality of random symmetric matrices over Z_p proved by Wood.