Tell me more about these images please. If these are the exact pictures you are going to use, what are you planning to use them for and are they copyrighted images? Did you add one of the figures or both to the scene? They are not similar and one must already be added with PS.
One way or the other, this is not a one-step process. There are enough differences between the two to require quite a bit of tweaking. Also, unless these are not full size, the resolution is absolutely terrible. Enlarging anymore than they already are will not work.
I did this and it is not very good, but it was a quick fix. The long-haired guy is very desaturated and getting the two skin tones the same is not worth it, IMO. In fact, unless you are simply using this as a practice to adjust color, tone, and contrast, IMO, the whole exercise is not worth your time.
Nevertheless. I used hue/sat layer adjustments on both images, and curves adjustments on the skin of the older guy as well as a hue/sat on that same selection. Unfortunately, I had to decrease the sat on the blue guy and I didn't play around with curves, but that would be my next step. I would not want to be tasked with doing this for real, as it would be a major headache. For what it's worth; my quick effort:
![ColorBG.jpg ColorBG.jpg](https://www.photoshopgurus.com/forum/data/attachments/28/28704-68088692f68f7fef82d834fd0109871f.jpg?hash=aAiGkvaPf-)