Robin managed about a dozen different figures even before the character went nuclear following The Lego Batman Movie, featuring the full gamut of his costumes from dippy Golden Age through to modern uberdarkness. The one that best fits a Titans lineup is probably the one from the Jokerland set; it's one of the few that doesn't seem to have been bootlegged, though it's easy to compile from various parts.
The figure finds a good balance with its' modern take on the classic figure including the short sleeves but not the exposed leg flesh and a trendy spiky hairstyle with the more modern take on the torso of the original character which excludes the lace-up collar but includes a more contemporary emblem.
The comic relief of both series (well, the extreme comic relief in the comedic Teen Titans Go!) thanks to the visual potential of his shapeshifting abilities, Beast Boy has been long established. There was a point in the eighties where DC tried to reinvent him as the inner darkness influenced Changeling but it never really caught on and if anything his comedy status seems to be a response to it. An official Minifigure came out as part of the same Jokerland set, though it's also been bootlegged.
Overall it's a good job, with most of the main visual points hit - a reuse of the "Thriller" Werewolf hairpiece even gives him pointed ears, though there's no sign of the character's tail. While the extant tail piece would be too large to work it's a shame there isn't even one painted on like there is on the Nightcrawler customs, especially as he has a coloured back. A nice touch though is the double-sided face, with a goofy face showing a tooth and a cocky expression both good choices.
One of DC's responses to the seriousness of the eighties was Cyborg, unimaginatively named even for the company behind Superman. Naturally he was a cyborg and he started out super-serious, though the cartoons toned this down a bit and there was some backwash to the comics as a result. An official figure has been made, bait in the Darkseid Invasion set (keeping heavweight company with Superman, the Green Arrow and, er, Hawkman) and also coming out in a Dimensions Fun Pack the same year.
The bootleg actually changes the figure's base colour entirely to silver-grey rather than black with silver paint apps. The result is a little more one note but actually more aesthetically pleasing and solid-looking. The rest is kept largely the same, including the excellent unique headpiece/helmet. Like most of the official figures of the era he has a reversible head with happy or angry expressions and came with one of the neat (gentle) working launchers.
Koriand'r is much like Powergirl in that she was basically invented as wank fodder for adolescent boys and has endured an uphill battle for credibility since, Red Sonja in space as her creators admitted. Some decent storylines have helped; wearing progressively fewer clothes has not. Thanks to her key roles in the cartoons, where she doesn't dress like a stripper even if she's often Robin's squeeze, she did get an official Minifigure as part of the Jokerland set with Beast Boy and her beau because the thing was ninety quid.
The costume chosen is one of the more dignified, again drawing more on the cartoon version, which is a plus. It's very nicely detailed with lots of silver accents, including on the arms which always makes a figure feel more dedicated and there's even an orange-tinged skintone used. Her super-long hair sadly can't quite be captured though the piece chosen is probably the most suitable and again she has the two-expression face. A fine figure.
Moderately popular as part of the comics universe, Raven's popularity went into overdrive after she appeared in the cartoon and like some of the others this bled backwards into print, including her much-modified physical appearance. This considered it's strange that she's the odd one out, with no official Minifigure having been released.
Instead the old combination of customisers and bootleggers comes into play. While there's nothing really in Lego's inventory for the full-length cape the combination of a hood and a cloak largely does the job while the paint applications largely do the job. Whoever designed it made the choice of incorporating the permanent shadow over the face which looks good but does mean that you can't remove the cowl and add purple hair as half of the head is black.