It seems you’ve gotten a lot of good advice about the leos, but I can help with the crested geckos. Geckos #4 and #8 are harlequins, and Gecko #7 is a tricolor harlequin (as you say). Gecko #6 is a flame, and Gecko #5 is a flame with some faint harlequin markings. For colors you will need to look at them when they are fully fired up to get a better sense. Gecko #8 is a male.
In terms of visible health issues:
Gecko #4 looks healthy from what I can see.
Gecko #5 has a lot of stuck shed that you should take care of ASAP. Put the gecko in a wet/humid container for half an hour or so and then use a damp Q-tip and, if necessary, tweezers to get all of that shed off. Then make sure you keep the humidity level up in the enclosure for a while to prevent any ongoing shedding problems. This one also looks very underweight to me.
Gecko #6 has a wavy tail, which indicates MBD. Give him/her extra calcium to prevent it getting worse. The skin looks wrinkly, which suggests dehydration, so keep the humidity up for this one as well. Make sure he gets a chance to lick up some water droplets when you mist.
Geckos #7 and #8 don’t have any obvious issues. It is hard to tell from the photos, but from the wrinkled bottom edge of their bellies I wonder if they are a little bit dehydrated as well. Again, it is hard to tell from the photos, but Gecko #8 might be a little underweight as well.
None of these issues are bad enough that any of these cresties would need to see a vet, though. A month or two of good nutrition (via a pre-formulated crested gecko diet from Pangea or Repashy) and proper humidity should fix everything except for the MBD. Hopefully the good nutrition plus some calcium supplement powder will at least stabilize the MBD and prevent it from deteriorating further.