The Super forms added heart buttons, wingy skirt details, gauzy shoulder pads and humongous back bows for all, as well as extra skirt colours, brooch details and hair accessories for the lead. Eternal Sailor Moon was the frilliest of all, with flying ribbons and wings everywhere. An episode of the first anime actually plays with it, when Usagi is unable to navigate a small room with many people (The Inners, Uranus, Neptune, The Starlights, two members of the Quirky Mini Boss Squad and the Monster Of The Day for a total of 13 people) without knocking things over. The sounds of objects breaking can be heard as she does her In the Name of the Moon speech (Though not seen due to stock footage). Thankfully the room in question is her family's dining room.
In a twist, everyone on the team (except Moon and Chibi Moon) gets more and more uniform as time goes by. Their super form takes away their (semi) unique chokers, brooches, and sleeves. Their manga-only third form (Which goes un-named in the manga) finishes the job by getting rid of their unique earrings and shoes, and makes their back bows all a lighter shade of their primary colors. Although each solider still has her own color scheme, their uniforms in the Stars manga are otherwise identical.
Chibi Moon matched Moon except for colors in her first two uniforms... then the 3rd made her identical to the other Senshi.
There does appear to be an upper limit, however, as Sailor Moon's final power-up illustrates; in the finale her costume crosses something akin to the Bishounen Line and she spends the episode naked save for great feathered wings and the Ginzuishou over her heart.
Interestingly, her implied final form in the manga, Sailor Cosmos, has a much simpler costume, dropping many of the excess ribbons, bows, jewels, and colors for an almost completely white uniform with simpler adornments and replaces the wings with a simple white cape.
Magical Girl Lyrical Nanoha : Variation due to target audience: The upgrades showcase additional metal pieces on the uniform and occasional sharp additions of fabric trim, and after the timeskip, shorter skirts. Though Fate Testarossa's initial upgrades add frills to her outfit as well, her last-resort Sonic Form reverses it, leaving her with nothing but skin-tight clothing "to make her faster".
Upgrades between the end of the anime and Force run away with the Mecha aspect of the show instead, having largely technological aesthetics.
Futari wa Pretty Cure Max Heart gave them more frills, and also covered up Black's stomach — the consensus is that parents had probably complained, as it wasn't until Yes! Precure 5 that Dream wore another midriff-baring costume.
Both Max Heart movies also had super forms. The Golden Power from the first movie just colored their clothes gold, but the Power of the Phoenix from the second movie fits this trope to a tee.
An odd twist occurred in Futari wa Pretty Cure Splash☆Star. The powerup happens as normal to Cures Bloom and Egret as they become Bright and Windy. However, when they relinquish the new powers to their original owners, their Bright and Windy costumes are rather plain. This brings up the horrifying notion of what adequately detailed costumes would have done.
In the Yes! Precure 5 movie, the team becomes butterfly-winged Super Cures, and true to form, they have too many frills to count. Dream, of course, has her own "special" touches as team leader. And in Yes! Precure 5GoGo!, the wings are gone, but they get jackets instead. Cure Dream's stomach goes the way of Cure Black, but parents probably didn't complain, since Milky Rose fills the niche there instead.
The Yes! Precure 5GoGo! movie pulls an Eternal Sailor Moon by upgrading Cure Dream into Shining Dream; the wings are indeed back.
And to disturbing levels in Smile Pretty Cure! with their Princess form and the upcoming "Hyper Princess" form.
Finally, Pretty Cure All Stars DX 2 and 3 both feature all of the previous super forms returning, with the addition of little gold wings.
Fushigiboshi No Futago Hime powers up its titular twins all through the two-season series, ending with a mess of lace and cute accessories.
Ojamajo Doremi: The uniforms in Sharp bear some resemblance to the S1 uniforms and their Royal Patraine uniform resembles the uniforms in Sharp. This is averted starting with Motto.
In Revolutionary Girl Utena, Utena goes through a transformation sequence prior to each of the many duels after her first, and it gets pretty damn elaborate later on; however, the only visible change in her outfit is the addition of a frilly trim and epaulets.
Shinzo: A rare male example is Mushra. His most powerful form is, in fact, his regular orange armour with pink frills added.
The heroes of Wedding Peach are supposed to be angels, and in the second season, their armor sprouts feathers from the shoulders. They can even turn into wings.
Cardcaptor Sakura: Despite the fact that Sakura's battle costumes changed constantly, it still managed to do this by moving the Fly card wings from the staff to Sakura's back during the Sakura Card arc.
In the Pretty Sammy OAV, Pretty Sammy transforms into Hyper Sammy before casting her Pretty Coquettish Bomber.
Saint Seiya: Another unusual male example: Seiya. At first, Bronze Cloths were fairly utilitarian pieces of armor: a chestplate here, shoulderguards there, shinguards over there, maybe asymmetrical gauntlets for style or protection. But as the Cloths were consecutively damaged, destroyed, repaired, and revived, they steadily became flashier and prettier. Most full-head helmets became tiaras, for instance. It all culminated in their transformation into "Divine Cloths" that came with wings, intricate (and pointless) decorative engravings on continuous surfaces, and curvy loops at the end of what used to be spikes or sharp edges.
Parodied in Kore wa Zombie desu ka?, where Ayumu's Masou Shoujo outfit keeps sprouting more ribbons and bows as he (yes, he) powers up, eventually prompting Haruna to scream, "Stop! You mustn't get any cuter!"
W.I.T.C.H.: When the title girls get new powers in the erm... 'New Powers' arc of the show, they get new outfits, with neat gloves, their own personal symbols on the costumes, bigger wings and Rapunzel Hair. As a bonus feature the new uniforms can actually defend the girls from attack by moving their many strips of cloth. Heck, they even accessorize with new weapons later on.
Often occurs, though the most common example is when the red ranger of the season, and sometimes one or two extra rangers of the team, receives the "battlizer", which is a set of extra armor which they wear over their regular costume.
The most "extra frills"-esque example is the Red Mystic Ranger in Mystic Force. When he becomes the Red Dragon Fire Ranger, much of his new form is simply extra frills.
City of Heroes, with its ridiculously extensive costume creator, encourages this. As you level up, you unlock additional alternate costumes and extra costume pieces.
In the Final Fantasy Tactics Advance series, the Ribbon is part of a series that increases in frilliness and power along the line: starting with a simple alice band, stepping up to a hair clip, and ending in a poofy hair ribbon. Each level up protects against more status effects, culminating in the Ribbon which protects against everything. To discourage the Ribbon being spammed, though, only female characters can wear it or its partners. Male Humes, Bangaa, and Moogles can learn a passive ability that will let them wear Ribbons in the sequel though.
In Twinkle Star Sprites, Load Ran transforms after stage 6 and looks considerably more developed in Sprites form.
Rare quadruple male example in 8-Bit Theater: the Light Warriors aquired class changes. These changes included new costumes, that looked suspiciously similar to their old ones, despite being clearly different.
Winx Club added brooches and purses to the fairy outfits for their first power up (Charmix). In season 3, however, they completely abandoned the Charmix and gave the girls totally new Enchantix outfits and powers, which meant a fresh start for the uniform. And in season 4, they once again abandon the Enchantix, replacing it with the Believix. There are also 2 sub-transformations, Sophix and Lovix, and no doubt seasons 5 and 6 will bring their own outfits - the episode guide for Season 5 mention Harmonix and Sirenix.