The 2000s, 5: Classic Hasbro
The whole time the Unicron Trilogy was rolling (and indeed before, as a pervasive rumbling underneath), there was talk of a live-action movie being developed. This undertaking missed the 20th anniversary mark, but eventually got some momentum under it and a calendar started taking shape for a summer 2007 release (pushed back from a late 2006 plan). This left a window in between what became the final leg of the Unicron Trilogy (Cybertron) and the Movie line, and this was filled with a line dedicated to revisiting and updating Generation 1. This speaks to where the brand team was at this time, where such a sure seller of a nostalgia mine was last-minute filler between lines that continued to build the road forward. There's a totally different balance these days (and both are solid status quos I enjoy, to be clear), but it's interesting to see the roots -- and, looking back, to see how a line intended to be a stopgap of sorts took on a life of its own, just like the previous one in RID2001 had.
Classics kicked off what fans would call the CHUG cycle (Classics, Henkei, Universe, Generations, with modern lines basically furthering Generations), and interestingly even the packaging had elements that would echo in lines to come.
As befits its planned status as a filler line, Classics started out modest, with just Deluxes and Voyagers, joined by Legends with Cybertron redecos and Mini-Con packs with new molds intended for Cybertron. These carded figures were on predominantly red cards with beveled, brushed-metal panels around the edges, with vents and faction-colored panels cut into them. These formed very tech/industrial-feeling borders that tended to follow packaging edges and add more corners and cutouts to them; these added good framing overall but sometimes felt a bit distracting.
The Deluxes were vertical cards shaped similarly to the Cybertron tapering trapezoid, with the toy packaged in vehicle mode. The top of the card had the cardboard dipping to form a lower edge, with clear plastic filling the space to form the J-hook/hang tab for hanging on pegs. Fancy. The logo was fairly straightforwardly aligned with the nostalgic nature of the line: the classic beveled Transformers logo (faction sigil included, based on the toy) with "Robots In Disguise" in yellow underneath. "Classic" only really appeared in a lower corner of the front in-bubble card (and on a panel of the boxed figures), labeling the toy as Classic Deluxe or Classic Voyager.
The character name, below the faction in a faction-color cut-out, was in yellow-glow-bordered faction-color text on a silver nameplate, next to a headshot of the robot mode fading in from the background (no character art). Interestingly, the character's function (Bumblebee has "Autobot Spy") is listed underneath the nameplate, a feature not commonly seen at that point.

A lot of this was retained for the Legends and Mini-Con cards, which were generally smaller versions of the Deluxe cards. The Mini-Con Team packs would list all members' names in the center below the team name, and the back would give one team bio and individual Technical Data.
Conversely, there would also be "larger" versions of these, which were basically (similar to how Cybertron and Universe did it) 2-packs of Deluxes on conjoined cards, with a label proclaiming them as a Value Pack.


Boxed figures (Voyagers) had much the same treatment, with a predominantly red design with the logo (such as it was) in the top center, above a large window (that tended to spill over to the sides) for the toy. The nameplate and the headshot are on our lower left. Like the Deluxe boxes, these were also similar in shape to their Cybertron predecessors, except for being flat instead of faceted on the front. The top panels had fairly large cutouts for clear windows as well. There were also Deluxe/Voyager and Voyager/Voyager two-packs, which received longer/wider versions of the Voyager box, with the two figures packed in robot mode and with large foldout panels (more on this below) covering the front window.
The back of the packaging (still back to English-only in relevant markets) tended to feature large pictures of either mode, with callouts for accessories and features, and labels for the altmodes (Bumblebee is a "Cruiser", and Optimus' cab is a "Tractor Trailer". Sure.). Very welcome among these was a sizeable bio (and quote!) and Technical Data. Co-sells would have a corner to themselves, and the neat new logo for the Transformers Collectors Club (and a keyboard key-esque logo for Hasbro.com) were also clearly visible. Mutlilingual cards would dispense with most of this, in now-familiar fashion, to fit the multitude of translations in.
Two notable things about Classics, other than the predominant red tone and preponderance of silver metal panels as border pieces, are [1] the use of fold-out panels with velcro closures and [2] the graphics used with the red/yellow backdrop. The latter is only really notable to me, but then, that's been the theme of this thread, no?
The fold-out panels were something we'd never really seen in Transformers packaging, due to a number of factors that probably included cost for the specific extra shapes and velcro and glue, and concerns about breakage in transit or on the shelf. But they were very neat. Deluxes and Voyagers alike received small panels on the front of the packaging that showed a toy photo of the altmode, with a helpful label inviting consumers to "FLIP FOR ROBOT MODE" (multilingual packaging just had arrows). (I flipped for the line as a whole, tbh.) Flipping the tag would show the promised mode, a nice and actually fairly unnecessary touch (particularly nice BECAUSE it was so extra).


The larger two-packs would take this up an order of magnitude, with panels covering half the box front opening like a pop-up book to reveal a large portrait of the toy on its side in robot mode (in a pose not really repeated from any of the other toy photos on the packaging), with Technical Data and a simple transformation sequence!


Sadly, this wasn't every two-pack, as the Ultra Magnus vs. Skywarp "Battle for Autobot City" pack was basically a wider version of the Voyager box (but with the trapezoid inverted, flaring out toward the base before tapering again). Likewise, the 5-pack for Constructicon Devastator avoided any such fanciness, being a straightforward box that packed the four limbs in altmode around robot-mode Scavenger.
The red-and-yellow backdrops are somewhat interesting in terms of the CHOICE of graphics to be used. These were, well, a bit unexpected. While the front of the card/inner box tray tended to have huge lens flares with crisscrossing lines to spotlight the altmode-packaged toy with not much more visible, the back of the packaging -- especially on the boxed figures -- tended to show us a bit more. Rather than the usual abstraction of a grid or central element that provided a glowing spotlight, the Classics card used a silhouette of what seemed to be a (ruined?) cityscape, with various archways and vertical structures, set at an angle. Overlaid on this was what seemed to be a scanline filter or two, with the lens flares also appearing with lower opacity. This apparently fiery battlefield was a low-key element to the Classics packaging I am still strangely drawn to.


This general trade dress would be applied to a lot of other products, similar to how the Universe (2003) packaging style was. This included the Ultimate Battle 2-pack, the 2007 Pepsi Optimus Prime (which received character artwork and a
refreshing cool nice-looking white-grid-on-BLUE-background twist), "Commemorative Edition" Soundwave (who also got the fancy fold-out panel treatment
and character artwork, the latter a staple of Commemorative Series reissues), and Masterpiece Starscream.
On that Masterpiece note, this packaging style was also applied to the "1986 movie's 20th Anniversary" rerelease of Masterpiece Optimus Prime (with DVD and display base), whose original packaging was decidedly different, being a more straightforward nostalgia-based look with the grid on red and a large window to show off the toy in robot mode (and a large Matrix graphic with text highlighting the 1984-2004 anniversary. The DVD-packed reissue, as well as the US release of Masterpiece Starscream, would start a trend of US-released Masterpieces generally adopting the packaging of contemporaneous main toylines. Interestingly, the packaging for Starscream in particular -- with the main "box" being a huge clear plastic window -- kind of evokes an approach to specialty packaging that would be more heavily used later on.


As noted, this was an overall packaging vibe that would influence the look of the US-based nostalgia line to varying degrees over about the next decade.