We know that Dreamers with the Talent can learn how to manipulate Tel'Aran'Rhiod using their willpower and intelligence, and it seems that Wolfkin have the ability to match or approximate what Dreamers can do using their insinct, but we really don't have a good approximation for what a trained human Dreamer with no Talent could accomplish.

It seems that many of the Forsaken have displayed the ability to enter Tel'Aran'Rhiod, but the only note we have regarding variations in their ability is that Moghedien and Lanfear were considered the most powerful of them in that realm. There may be limitations to what a Dreamer with no Talent can do there...perhaps this is why Slayer fell into the nightmare so easily and was unable to free himself?

Further, we know from Egwene's POV that she knows that stopping balefire is possible, with her surprise merely being that Perrin displayed that ability despite not having any of her equivalent training - tellingly, her next thoughts are that she was both a channeler and a Dreamer, and certain things were easier using one or the other skills to manipulate T'A'R with a specific mention that she had to stop thinking like a channeler (i.e. blowing out a wall is easier to do with the Power than to imagine the wall exploding). A Forsaken might merely be able to enter the Dream to various degrees and use the One Power as a crutch to influence the landscape there versus using their willpower or instinct to do the same.