If you extend your thinking a bit, you can get right back to your answer without needing to include evil.
Imagine that the genius of evolution sees things beyond the immediate survival of the next moment, and is mapped onto a greater survival of the species - and not just necessarily for tomorrow, but for the day after that as well - and (I don't know the accepted scientific position about this) that evolution is concerned with the survival of the species in the most logical and pragmatic way possible (I realize I am personifying something that is in no way a person).
This must be the case in some way or another - otherwise intellect would have much less value as a survival skill. Once you learn how to skin the cat, the one who's best at skinning should survive - and that would be the strongest or fastest.
We are a communal species. Hitler (for example) -- actually he's overused and undeserving of all the chatter -- let's use Pol Pot -- Pol Pot was certainly an evil individual by almost any possible definition - by wholesale slaughter and oppressive policies that lead to starvation and malnutrition, he was responsible for between 3 and 8 million deaths. His evil was a pure demonstration of survival of the fittest (although in this case the fittest were by no means necessarily superior in any way) or survival of the powerful.
If he continued, and others like him persisted to succeed in molding the world according to their whim - eventually humanity would kill itself off entirely. Atom Bombs or Country-wide gas chambers or something worse - the powerful would seek more power - and eventually humans would disappear or be seriously diminished.
I realize here, that I'm taking extreme liberties with how I interpret evolution - but for the sake of making a point without knowing many important details, let's call this a metaphor.
In the metaphor of Pol Pot the fittest and others like him, it is too easy to imagine the eventual destruction of our entire species. It probably came closer than we can imagine - and perhaps the Cuban Missile Crisis is a perfect example of evolution by kindness (not really - but thoughtfulness or responsibility). Were Kennedy or Khrushchev driven solely by the maintenance of power (i.e. surviving their power), then almost certainly, something existentially devastating would have taken place. The survival of our species would have been threatened, and the Will to Power would have produced an effect that was contrary to the intentions of evolution.
What ruled the day in that instance was the power of compromise,long-term thinking,rationality,and humanitarianism (If you read the play by play events surrounding the crisis, it's really quite inspiring). What prevailed - what furthered the survival of not just the individuals involved, but our entire species, were traits that are not associated with evil or power, but traits that are associated with concern for our fellow man; traits that are associated with goodness and perhaps even (sometimes) weakness.
Human evolution appears to be something different (or at least from where I look) than traditional dominance based evolution we are most familiar with. While the strongest, fastest, and most dominating animals in many species must be the ones who survive to procreate; in our species we have developed traits and capacities that extend beyond our physical attributes and it is the survival and evolution of those very traits that determine the boundaries of being human.
Unlike shark or alligator offspring, no human can survive on their own(*there are a few notable exceptions - see The Cambodian Jungle Girl - but in her case and every similar case, the feral child is more like an animal than a human being), and thus we depend on the survival of our species for our own individual survival. More specifically; even if all of us could survive individually (surviving the body) - that which makes us human (surviving the mind or the spirit) can only survive in community, and thus what survival of the fittest means for the evolution of our species can only be understood in terms of the survival of humanity as a whole.