You can create a generic monad transformer as long as the "inner" monad has a Traverse instance

MonadTFromTransformer.scala

import scalaz._
import Scalaz._

object MonadT {
  implicit def monadTransformerFromTraverse[M[_]: Monad, N[_]: Monad: Traverse]: Monad[({type MN[A]=M[N[A]]})#MN] = new Monad[({type MN[A]=M[N[A]]})#MN] {
    def point[A](a: => A): M[N[A]] = a.point[N].point[M]
    def bind[A,B](fa: M[N[A]])(f: A=>M[N[B]]) : M[N[B]] = {
      val M = implicitly[Monad[M]]
      val NT = implicitly[Traverse[N]]
      val N = implicitly[Monad[N]]

      M.map(M.join(M.map(M.map(fa)(N.map(_)(f)))(NT.sequence(_))))(N.join)
//                       |- => M[N[M[N[B]]]]  -|
//                 |-       => M[M[N[N[B]]]]                   -|
//         |-               => M[N[N[B]]]                       -|
//    |-                    => M[N[B]]                                  -|

    }
  }

  def main(argv: Array[String]) {
    val x: Option[Option[Int]] = Some(Some(1))
    val f: Int => Option[Option[Int]] = { x: Int => Some(Some(x+1)) }

    val MT =  monadTransformerFromTraverse[Option, Option]
    println(MT.bind(x)(f)) // Some(Some(2))
  }
}