Unwanted hairs can be removed with lasers, it is done in sittings. Number of sittings depend on density of hairs and thickness. You can get rid of regular shaving or waxing of underarms and bikini area specially in females.
Tattoos are difficult to remove but some tattoo inks are very sensitive and good results can be obtained with judicious selection of lasers. Similarly some scars do well with lasers and some will not. Here comes the wisdom of a plastic surgeon as to which modality should be chosen.