video game machine Video Game Website Use Of Video Game Images

I am helping a friend of mine to make a video game website.He will use the combination of his youtube game review channel and website to build his own review authority.We 've all noticed that many (if not all) other game review sites have a lot of images from video games, including covers, screenshots, etc.
Does anyone know if most of these sites are infringing copyright?If my friend avoids using images from these video games in your opinion, though it would seriously hurt his post as he will have a featured post slider to show the image, it would be a bit odd if he could not use the image of the game or part of it as his image for comment