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[[quoteright:315:[[Anime/MobileSuitGundamSEED http://static.tvtropes.org/pmwiki/pub/images/ButterflyWings_7443.jpg]]]]
[[caption-width-right:315:[[SarcasmMode Like that flight pack actually makes it aerodynamic now...]]]]

Whenever the plot of a Mecha series calls for a MidSeasonUpgrade you can tell there will be changes. However adding new powers to an existing robot will often require scrapping the old design altogether and bringing in a shiny new one, and this is not always convenient. One of the easiest ways to get around this is a separate add on, that can be used to grant the new powers, simply by attaching it to the existing robot.

Adding a flight mode to a previously land-bound machine is a favorite. Sometimes this add-on will be a separate vehicle that is piloted by another character, combining (pun originally accidental but we're keeping it) this with CombiningMecha. Since most [[RealRobotGenre real robots]] are modular and reconfigurable to begin with (just like the expensive model kits they're hawking,) this is pretty much standard operating procedure for them.

MerchandiseDriven franchises love these, mainly because it means they can release the expansion packs as separate sets, without causing the demand for the older sets to stagnate.

If there are more than one expansion pack, expect to see MultiFormBalance kick-in. MetaMecha is an extreme example of this. Compare FrillyUpgrade, the MagicalGirl equivalent.

----
!!Examples:

[[foldercontrol]]

[[folder:Anime & Manga]]
* The ''Mazinger'' franchise:
** ''Anime/MazingerZ'' is probably the codifier of this trope: its Jet Scrander is basically a giant robot-sized jetpack, and it was created when [[BigBad Dr. Hell]] started creating more and more flying [[{{Robeast}} Mechanical Beasts]], as Mazinger was helpless against aerial attacks. WordOfGod said that [[Creator/GoNagai he]] always intended for Mazinger to fly, but first he needed to establish that Mazinger was ''heavy'', so he withheld the Jet Scrander until it was clear that the mecha was not light.
** The other Mazingers had them, too. ''Anime/GreatMazinger'' introduced Great Booster, which was a separate jetpack which doubled as a ramming weapon. ''Anime/UFORoboGrendizer'' had the Double, Marine and Drill Spazers, allowing the titular robo to fly, traverse the seas and burrow underground. ''Anime/{{Mazinkaiser}}'', or at least it's OAV version, had the Kaiser Scrander, which functioned the same way as Jet Scrander, though it also doubled as a ''boomerang''!. And finally ''Anime/ShinMazinger'' introduces an upgraded version of the Jet Scrander called the God Scrander that, in addition to flight, allows Mazinger to [[TransformingMecha transform]] into ''a giant RocketPunch''.
* ''Anime/KotetsuJeeg'': Jeeg had first the Jeeg Drills, a set of weaponized rockets that doubled like ThisIsADrill, and later it had the Earth, Marine and Sky parts, three sets of armor let the HumongousMecha fighting in land, sea and air, and [[TransformingMecha transforming]].
* Shoutmon from ''Anime/DigimonXrosWars'', being a CombiningMecha themed Digimon, has this. Generally the base form is [=Shoutmon X3=], he gains a sword in [=Shoutmon X4=] by combining with Starmon + Pickmons, adds speed due to centaur feet plus cannons in [=Shoutmon X4B=] by combining with Belzeebumon, adds a shield with a huge cape for [=Shoutmon X4K=] by combining with Knightmon and [=PawnChessmons=], adds a spear for [=Shoutmon X4S=] by combining with Spadamon, and finally gains jet packs, a blaster, a shield, and a power increase for [=Shoutmon X5=] by combining with Sparrowmon. Let's not even go to the combination beyond X5...
* One variant on the G-Armor in ''Anime/MobileSuitGundam'' basically allowed the Gundam to ride ''in'' it, converting it into an impromptu fighter jet. Axed in the movie versions, like the infamous Gundam Hammer.
** On a more realistic note is the G-Defensor in ''Anime/MobileSuitZetaGundam'', which combined with the Gundam Mk. II. The [[ExpandedUniverse sidestory]] ''Advance of Zeta: Traitors to Destiny'', a RedShirt mech Nemo can use it by equipping with Gundam Mk. II's backpack[[note]]This should work for the GM III as well, since it's equipped as standard with a copy of the Gundam Mk. II backpack, but it's yet to happen in canon.[[/note]], while ''VideoGame/SDGundamGGeneration'' gives the Rick Dias its own D-Defensor.
** The [=GP03=] ''Dendrobium'' from ''Anime/MobileSuitGundam0083StardustMemory'' is somewhere in-between this and MidSeasonUpgrade, with a generous helping of CoolShip. The [=GP01Fb=] plays it straight, though.
*** The [=GP01Fb=] is an odd duck; originally, the [=GP01=] could be configured for space combat simply by giving it a new Core Fighter (in other words, a classic MechaExpansionPack). However, Kou gets the Gundam trashed by trying to use it in space without the pack, so Anaheim Electronics rebuilds it into the Full Vernien, which is more of a half-MidSeasonUpgrade. The manga retelling, ''Rebellion'', gives the GP-01 the Full Armor gear that was once meant for the original Gundam.
** The [=ReGZ=] from ''Anime/MobileSuitGundamCharsCounterattack'' combines this with TransformingMecha - literally. Its flight form is achieved by docking it with the Back Weapons System, which is basically a nosecone, wings, and beam cannons that dock with the backpack. This allows for capability similar to the [[SuperPrototype Zeta Gundam]] without the complex and highly expensive transformation system. The Scorpio from ''Anime/MobileSuitGundamWing'' uses the same concept.
** ''Anime/MobileSuitGundamUnicorn'' has the Stark Jegan, which is a slightly tweaked Jegan with fitted new armor and armaments. The added equipment [[ShedArmorGainSpeed can be jettisoned if needed for a boost in speed]].
*** Unicorn itself receives an upgrade to "Full-Armor Unicorn", which is Unicorn with about [[MoreDakka fifty-bazillion guns]] on its back.
*** The Banshee also gets an upgrade into the Banshee Norn: it ditches the scattershot beam rifle and claw hand in favor of a multi-purpose rifle/grenade launcher and a booster on its back, as well as a greatly improved Psycoframe interface.
** The (short) manga and model series ''Gundam F90'' has the eponymous Gundam, which is fairly orthodox except for the hardpoints spread about its body which allow it to equip a staggering variety of weapons and gear.[[note]]A grand total of 26 forms, one for each letter of the alphabet, though only about 10 were ever detailed.[[/note]] In the manga, none of the actual packs are used; instead, for the FinalBattle the hero equips parts piecemeal from three different packs, to achieve a "Full Weapons" configuration.
** The [[Anime/MobileSuitVictoryGundam V2 Gundam]] received the Assault and Buster variants, a melee to mid-range and long-range power-up respectively, and could even equip both outfits at once (giving it the cumbersome name of V2 Assault Buster Gundam). However, the energy requirements and additional weight of the packs lowered the V2's max specs at the same time...
*** The Overhang Pack of the original V Gundam and the AceCustom V Gundam Hexa is also this, as it gives the Gundam extra boosters as well as two powerful beam cannons for long-range assault. Attached to a regular Core Fighter, the Overhang Pack turns it into a Core Booster.
** And the G-Falcon of ''[[Anime/AfterWarGundamX Gundam X]]''. A better example appears earlier though, the Gundam X Divider which adds the "Beam Harmonica" Divider shield, a double barreled beam machine gun, a second beam sword, and better thrusters.
** ''Anime/MobileSuitGundamSEED'' loves this trope so much, it married it. The Strike Gundam started the trend with its Striker Packs, including the main three.[[note]]Aile ("wing"), Sword, and Launcher. In the first series, the Aile pack only permitted Strike to fly in space, giving it rocket-assisted and sustained leaps on Earth, this was largely ignored in the second series.[[/note]] Several more MS pop up with follow the "flight[=/=]melee[=/=]gunner" set-up, including the Impulse Gundam's Silhouettes and ZAKU Warrior[=/=]Phantom's Wizard Packs from ''Anime/MobileSuitGundamSEEDDestiny''. And that's not even factoring in all the ''other'' Strikers, Silhouettes, and Wizards that show up in side-media, or the mecha that don't quite fit the same dynamic, like the Dagger L and Windam[[note]]which have the Jet, Cannon, and nuclear missile Strikers[[/note]] and the Akatsuki.[[note]]which has its own custom flight and AttackDrone Strikers.[[/note]]
*** Duel has the "Assault Shroud", a set of armor for the [[MasterOfNone otherwise unspectacular]] GAT-X102, giving it heavier defenses and armor plates, greater movement and agility in space and extra weaponry.
*** The manga retelling, ''Gundam SEED Re:'' gave specialized packs to the Aegis, Duel, Buster and Blitz.
** ''Manga/MobileSuitGundamSEEDAstray'' tries to justify this with the two main Gundams. Blue Frame's special trait is that its computer is loaded with specs for a staggering variety of mission packs, including amphibious armor, jungle gear, etc., which fits its adaptable mercenary pilot Gai like a glove. Red Frame also gets a fair number of add-ons, mainly because its pilot Lowe is an enthusiastic mechanic and just plain loves building stuff like [[MetaMecha a Power Loader]] and [[{{BFS}} 150-meter-long katana]].
** The grand-champion mecha for expansion packs in the Seed-verse is the Astray Out Frame, equipped with a "Multi-Striker System" that allows it to load ''any'' of the expansion packs in the series: Striker packs, Impulse Silhouettes, Tactical Arms, and ZAKU Wizards, as well as a couple of packs custom-built for it.
** Play straight with Freedom and Justice in ''Anime/MobileSuitGundamSEED'', Strike Freedom and Infinite Justice in ''Anime/MobileSuitGundamSEEDDestiny'' with their METEOR weapon systems. It's pretty much the same in both series, but their destruction in the finale of Seed lets them bring them out again for the finale of Destiny.
** The trend continued in ''Anime/MobileSuitGundam00'' with GN Arms and 0 Raiser for Exia, Dynames, and 00 Gundam.
** The Arios' GN Archer, which is both a MechaExpansionPack ''and'' a TransformingMecha. They remain linked during regular flight and separate during combat in order to conserve on the GN Archers particle tanks.
** Played straight one more time towards the end of the series, long ''after'' the MidSeasonUpgrade. Most of the Gundams received add-on weapon and equipment packs (the 00 just got a new sword and the 0 a new battery pack) in time for their swansong.
** ''Anime/MobileSuitGundamAGE'' has this all over the place with the Wear Parts produced by the AGE Device. The Gundams can swap out arm and leg units to gain new weaponry and abilities. The AGE-1 and AGE-3 Gundams swap out the parts depending on the situation. The AGE-2 more or less kept its only set of Wear Parts as a permanent upgrade. Some episodes show that even the {{Mook}} mobile suits on the Federation's side can be equipped with Wear Parts if needed.
** The [=MSVs=] for the Gundam series, as befitting their MerchandiseDriven status, usually reveal that certain units have had additions, usually extra armor, that was planned but was ultimately scrapped or used by someone else other than the intended pilot.
** The manga ''Gundam EXA'' adds a couple of interesting spins on this: the series is set in the distant future of the entire Gundam timeline and revolves around G-Divers who explore recorded memories of the past ''Gundam'' stories. Thus, TheHero's Gundam has Mecha Expansion Packs explicitly based upon famous Gundams, including a melee form based on the [[Anime/MobileFighterGGundam Shining Gundam]], a long-range form based on [[Anime/MobileSuitGundamWing Wing Zero]], and an AttackDrone form based on [[Anime/MobileSuitGundamSEEDDestiny Strike Freedom]]. On top of that, when he uses these packs, he [[SplitPersonality takes on aspects of the original pilots' personalities]], becoming HotBlooded like Domon Kasshu, [[TheStoic stoic]] like Heero Yuy, or hopeful like Kira Yamato.
* When not fully combined as Anime/GaoGaiGar, [=GaiGar=] could also equip Stealth Gao as a jetpack or Drill Gao for extra punching power. Arguably, Final Fusion itself counts, as well as for any other CombiningMecha who combine in this way. Also, when the Goldion Hammer is introduced, another robot is introduced with the express purpose of being [=GaoGaiGar=]'s hand when he's using it.
** The MidSeasonUpgrade (as it were) was pretty much sticking giant rockets onto [=StealthGao=], adding some extras to the RocketPunch and Protect Shade and changing their names. A new mecha (and toy) would have to wait for ''FINAL'''s [=GaoFighGar=]. Genesic [=GaoGaiGar=] is also effectively this, as it primarily adds the [[SuperPrototype original]] Gao Machines to [=GaiGar=].
** The Symmetrical Dockers all got pairs of thruster packs on their shoulders to maneuver in space during the second half of the show's run.
** Speaking of FINAL, Genesic [=GaoGaiGar=]'s counterpart to [=StealthGao=], known as [[MeaningfulName GadgetGao]], took the form of an enormous mechanical bird. While it itself did not count as an expansion pack since (like the [=StealthGao=] series) its jet engines formed [=GaoGaiGar=]'s forearms, it could detach its head and sections of its neck which would then transform into "Gadget Tools", including the Bolting Driver (a SuperPrototype of both the Dividing and Gatling Drivers), a Will Knife sized for Genesic's hands, and a pair of claw-like gloves that were used during [[DangerousForbiddenTechnique Hell]] [[YinYangBomb and]] [[FinishingMove Heaven]]. And let's not forget [[spoiler:the [[DropTheHammer Goldion]] [[UpToEleven Crusher]], an energy mallet that dwarfed Genesic [=GaoGaiGar=], which was made of ''three'' GGG space-ships and controlled by Mikoto (who was hooked up to it) and Goldymarg's Super-AI.]]
* All the ''Anime/BraveSeries'' have a expansion for their mechs. Mostly, the 3-member squad (not the main hero mech) gets one every time. Examples include:
** ''Anime/TheBraveExpressMightGaine'': Horn Bomber for Tri Bomber
** ''Anime/BravePoliceJDecker'': Drillboy for Build Tiger/Tiger Gimlet
** ''Anime/TheBraveOfGoldGoldran'': Fire Silver for Silverion
** ''Anime/BraveCommandDagwon'': Dag Drill for Liner Dagwon
* This is the defining characteristic of Liger Zero in ''Anime/ZoidsNewCentury'': it has three different such expansion packs, in addition to its base state. In model line, it also has Zero X armor. As well as the Fire Phoenix and Jet Falcon, separate Zoids that combined with the Zero from ''Anime/ZoidsFuzor''.
** Other Zoids can be modified in various ways - [[GirlWithPsychoWeapon Leena]] has her Gunsniper modified with [[MoreDakka twin]] [[GatlingGood gatling guns]] and [[MacrossMissileMassacre missile pods]], Blade Liger can be equipped with boosters with built-in beam cannon. See [[http://zoids.wikia.com/wiki/Zoids_Customise_Parts this]] and [[http://zoids.wikia.com/wiki/Blox-CAS#Blox-CAS this]] for some examples.
* Nearly every unique mecha in ''Anime/CodeGeass'' eventually gains flight capability thanks to a bulky "Float Unit". The Lancelot later receives a shoulder-mounted "[[{{BFG}} hadron cannon]]" as well - referred to as "Conquista formation".
** ''[[OddlyNamedSequel Code Geass R2]]'' eventually stops doing this though - the Lancelot is replaced by the Lancelot Albion, which uses a lightweight "Energy Wing System". The Guren is severely modified, if not completely rebuilt, (as the Guren SEITEN) with the same system a few episodes before this.
** Though R2 also shows how you can make adding such an expansion as awesome as possible: The Guren gets its Float Unit and a new radiation wave arm delivered and attached ''by missiles'' while ''falling from the sky down to the sea''.
* The F-Type Equipment from the ''Anime/NeonGenesisEvangelion'' ExpandedUniverse and ''VideoGame/SuperRobotWarsAlpha 3'' is a set of armor and weapons for the EVA-01(!) that also [[spoiler: actually prevents it from going berserk no matter what]]. The weapons also include a new rifle with a huge bayonet, N2 rocket launcher AND an AT field lightning weapon called the "Impact Bolt" mounted in the unit's shoulders, the strongest weapon in the entire franchise. [[https://www.youtube.com/watch?v=7TEpuD6g3Qo To say those last two create very large explosions when used is a complete understatement]]
** What about the D-Type Equipment from the original? Probably counts as a subversion, considering how goofy it looks.
** Also, the S-Type Equipment for Unit-02 in ''Anime/RebuildOfEvangelion'', which gives it flight capabilities.
** ''Anime/RebuildOfEvangelion'' also gave us the G-type equipment used by Unit-01 during the sniper battle against Ramiel, which consists of an advanced fold-down targeting scope that covers the eva's eyes and a radar antenna array, all mounted on the right [[VerticalMechaFins shoulder fin]].
* ''Anime/{{Macross}}'':
** The [[Anime/SuperDimensionFortressMacross FAST Pack System]][=/=][[{{Anime/Robotech}} Super Veritech]] gives the [[TransformingMecha Valkyrie fighters]] improved maneuverability in space and increased weapon loadouts. There was also the Armored Valkrie/Veritech which added armor and a whole lotta missile launchers, but rendered the mecha unable to transform out of battloid mode until it was jettisoned.
*** HilariousInHindsight but the former is actually ''TruthInTelevision'': the real life F-15C was designed to be compatible with the optional "[[FunWithAcronyms Fuel And Sensor Tactical]]" equipment which is actually a fancy name for auxiliary fuel tanks designed to reduce air drag and radar signature when compared to regular external fuel tanks at the expense of being non-removable without a ground crew. They originally wanted to pack navigational and infrared targeting systems into it as well but that was scrapped. What makes it count is that when ''Macross'' came out, the F-15 was still brand new so Creator/ShojiKawamori might have used it for inspiration.
** The VF-25 Messiah fixed the problem with the Armored Pack in ''Anime/MacrossFrontier'', allowing it to transform into fighter and GERWALK modes while still using it. The VF-171's also wind up picking up special anti-Vajra modules late in the series run.
*** The Messiah actually has three packs total, the Super Pack, the EW/ELINT version of Super Packs used to control several GHOST unmanned fighters, and the aforementioned Armored Packs. These Packs however, cannot be used within atmosphere and must be ejected prior to re-entry. They seem to be equipped with a "Smart" System allowing the Pack parts to coalesce into a single unit in low-orbit to be later retrieved when the [=VFs=] go back to outer space. This unfortunately also shows the limitation of the Pack system, as the VF-25's main rival, the VF-27 Lucifer, has all its armament stored internally, giving it less ammo and total offensive capability overall, but gives it a Jack of All Trades trait, enhanced by its Cyborg-enhanced piloting system. Most importantly, it allows the pilot a full range of offensive options even within atmosphere while the Messiah can only retaliate with its gunpod.
** In ''Anime/MacrossZero'' (chronologically the first series from an in-universe standpoint), Roy's VF-1 is fitted with what seems to be the precursor to Armored Valkyrie. Instead of having missile launchers all over the place however, it is also fitted with Reactive Armor, the ballistics-defeating kind of armor used on modern day battle tanks. This allowed Roy to not only ambush the two main villains with Proto-Armored Valkyrie's massive missile arsenal, but also survive their team attack due to the reactive armor.
** In ''Anime/Macross7'', Fire Bomber eventually picked up booster units for their custom fighters, enhancing their effect against the Protodeviln.
* ''Anime/TengenToppaGurrenLagann''
** Gurren Lagann picks up the ability to fly in episode 13, although this is a unique case in that rather than having a flight unit designed for it, Gurren Lagann ''commandeers'' a flying enemy Gunmen and assimilates it (which is really how Lagann combines with everything).
** The Lagann is the mecha, EVERYTHING ELSE is its expansion pack. Seriously, that's the whole point.
** The Space Gunmen are giant robots FOR the giant robots, which are basically the same machines but much larger.
** And the Arc-Gurren Lagann, which is like a space gunmen for Gurren Lagann itself, except its slightly bigger and looks different. And the there's the Chou Ginga Gurren Lagann... [[MetaMecha which is piloted by the Arc Gurren Lagann, which is piloted by Gurren Lagann. Many, many expansion packs.]] It goes all the way up to "SUPER TENGEN TOPPA GURREN LAGANN" that's pretty much, made of win and running on awesome.[[labelnote:*]]For elaboration, the Super Tengen Toppa Gurren Lagann is a hundred times the size of the regular Tengen Toppa Gurren Lagann, which is ''as big as a galaxy'', is made out of blue fire, and looks like [[MemeticBadass Kamina]]. [[CrazyAwesome Yes.]][[/labelnote]]
** In an example that can be installed at will, Kittan can upgrade his King Kittan into the King Kittan Deluxe by having his sister [[TransformingMecha transform]] her Kiyalunga into a shield and lance for him to use.
* Part of the whole point behind the "Hecatonchires" system in the ''Manga/{{Appleseed}}'' manga. With it, a cyborg can have several attachments hooked up directly to his body, and control them as easily as his own arms and legs. Reportedly, a 'Borg with the system could run an entire Aircraft Carrier by himself.
* ''Anime/FafnerInTheAzureDeadAggressor'' has an unusual case: the eponymous mecha has its air upgrade not so much attached to it as ''vice versa''.
* ''Anime/{{Zentrix}}'' Zeus and quantum both get flight gear to go into space.
* ''[[MagicalGirlLyricalNanoha Mahou Senki Lyrical Nanoha Force]]'' has started blurring the lines between MagicalGirl and MechaShow by equipping the title character with [[http://danbooru.donmai.us/post/show/735440/absurdres-highres-kurogin-mahou_senki_lyrical_nano this]] monster.
* ''Anime/StellviaOfTheUniverse'' - the Infinity has a whole kit of optional parts including boosters and laser cannons.
* Asurada GSX from ''Anime/FutureGPXCyberFormula'' receives two expension packs: the "Rally" and "Aero" types, which are used in the second and third races to fit different racing situations.
* The Aestivalis in ''Anime/MartianSuccessorNadesico'' have an odd variation of the expansion packs: they have various frames designed for certain areas (land, air, space, the Moon), but the frames are the ''bodies'' - the crew just swap the Assault Pit (the head and the cockpit) from one frame to the next. Doesn't work very well when there's a need to swap on the fly, shown by Gai's Cross Clash attempt.
* ''Anime/GearFighterDendoh'' had an odd case with the Full Armor package - a Super Robot homage collection of weapons and gear when the Data Beasts abandon the heroes when the plunge into the DespairEventHorizon.
* In ''Anime/PanzerWorldGalient'', the titular mecha got the "Assault Galient", a combination of assault rifle and ShoulderCannon.
* ''Anime/TimeBokan24'' has the main TransformingMecha Mechabuton, and a wide array of other bug-themed ones that can be used for two kinds of combinations. Super Docking enhances it in vehicle form, offering things like a PowerFist or turning it into an elephant, while Cosplay Docking offers a more typical expansion-pack type powerup, drawing on everything from pirates to samurai to salarymen.
[[/folder]]

[[folder:Fan Works]]
* In ''Fanfic/ThousandShinji'', after [[EldritchAbomination Ramiel]] melted Unit-01's armor, the Evas got the L-Type Equipment: new, sturdier armor, and new, more dangerous weapons.
[[/folder]]

[[folder:Live-Action TV]]
* Numerous ''Franchise/PowerRangers'' and ''Franchise/SuperSentai'' series use this mechanic when a SixthRanger joins up. The very first was Super Live Robo of ''Series/ChoujuuSentaiLiveman'', which combined the initial robot Live Robo and the robot of [[ThreePlusTwo the new guys]], Live Boxer.
** In the first season of ''Series/MightyMorphinPowerRangers'', the Dragonzord could either be combined with the Mammoth, Saber-Toothed Tiger, and Triceratops Zords to make a new humanoid machine, or truer to the trope, combine with the completed Megazord as an extra weapons pack (this wasn't often used because the Zyutei Daizyujin (Mega Dragonzord) costume was extremely cumbersome). The Falconzord from the third season could also combine with the Ninja Megazord as a jetpack, or the Shogun Megazord as a set of chest-mounted guns. '''Ultimate''' Daizyujin (Ultrazord) was used once in ''Zyuranger'' to eliminate Great Satan, but used repeatedly in Mighty Morphin Power Rangers through the remainder of season 1 (the majority of the "Zyu2" footage).
** Some seasons go a bit crazier with it, and ''numerous'' new Zords are introduced, each attaching to the standard formation in a way that adds one or two new capabilities. Eventually enough show up for the new ones to make their own formation, but that usually waits until near-midseason. ''Series/PowerRangersLightspeedRescue'' and ''Series/PowerRangersOperationOverdrive'' didn't stop bringing out new formations until near the ''end'' of the series.
** ''Series/HyakujuuSentaiGaoranger'' and ''Series/PowerRangersWildForce'' were probably one of the best examples of this, since each new zord provided a new weapon or upgrade specific to the animal in question. The long trunk and large ears of the elephant became a sword and shield, the long neck of the giraffe became a spear, and the horns of the deer created a claw/clutcher. Still overdone, but there was a certain pattern to it. Nonetheless, the greatest criticism about ''Wild Force'' is that it was more about its Mecha Expansion Packs than its story or characters.
** ''Series/EngineSentaiGoOnger'' (aka ''Series/PowerRangersRPM'') sets the new record, though, with [=EngineOh G12=], the series' largest combining mecha yet in terms of individual components--as the name suggests, it's formed by combining 12 Engines (that can form ''four entire separate robots!'') into what has been described as a member of Team Hilarious Overkill.
** ''Series/KaizokuSentaiGokaiger'' went all-out with this, as the Mecha Expansion Packs are in fact Legend Mecha used by previous teams (like ''Series/MahouSentaiMagiranger''[='s=] Magi Dragon or ''Series/TokusouSentaiDekaranger'''s PAT Striker), which the Gokaiger unlock after winning the approval of their predecessors. The season's requisite Ultrazord, Kanzen[[note]]Complete/Perfect[[/note]] Gokaioh, is made by combining the main robot, the SixthRanger's robot, and the ''Go-Onger'' Legend Mecha, and is of course just as ludicrously large as the [=EngineOh G12=], capable of movement only by using foot wheels.
** ''Series/ResshaSentaiTokkyuger'' seems to be headed this way. The Rangers' base is a CoolTrain with five cars, each in one of their colors, which turns into the expected mecha. However, from the earliest episodes, they keep finding new ones that add a new power to the main formation, and it's episode ''nine'' when they can form a second robot of their own, and [[spoiler: in episode 11, both robots combine]]. Last time it happened this early, it was, well, Go-Onger. Then episode 23 comes along and the main robot, the auxiliary robot, and the SixthRanger's robot all combine...
*** Heck, in ''Film/HeiseiRiderVsShowaRiderKamenRiderWarsFeaturingSuperSentai'', [=ToQ-Oh=] ends up combining with [[Series/KamenRiderDenO the Den-Liner]]... first as its head, then as its ''feet'' when [[Series/ZyudenSentaiKyoryuger Kyoryu Ressha]] butts in.
* ''Series/KamenRiderKuuga'''s beetle robot Gouram can attach itself to his CoolBike [=TryChaser 2000=] and become armored [=TryGouram=]. Turn out to be AwesomeButImpractical though, as [=TryChaser=]'s chassis got damaged by combination process. The MidSeasonUpgrade [=BeatChaser 2000=] fix this problem.
* ''Series/TomicaHeroRescueForce'' features a wide selection of vehicles that can combine with Rescue Striker, Rescue Saver, and Rescue Diver ([[AllThereInTheManual Apparently]]).
[[/folder]]

[[folder:Tabletop Games]]
* ''TabletopGame/{{Mekton}}'' has "Command Armor," which can fit any system in the game, and "Boosterpacks," which are specifically for extra speed. Both systems have a "balance modifier" that subtracts from the mecha's statistics, and can be balanced out with vernier motors and other such systems.
* ''Anime/FutureCardBuddyfight'' has [[http://buddyfight.wikia.com/wiki/Ultimate_Card_Burn Ultimate Card Burn]], a CombiningMecha Made of [[http://buddyfight.wikia.com/wiki/Card_Burn Card Burn]] and [[http://buddyfight.wikia.com/wiki/Card_Serpent two]] [[http://buddyfight.wikia.com/wiki/Card_Rhino other]] monsters. A few sets later, [[http://buddyfight.wikia.com/wiki/Card_Wyvern another card]] was released which combines with Ultimate Card Burn to give him [[http://buddyfight.wikia.com/wiki/Ultimate_Card_Burn,_%22D-Wing%22 a flight pack.]]
[[/folder]]

[[folder:Video Games]]
* While not technically an expansion pack, [=KOS-MOS=]' Tertiary Weapons System in the ''VideoGame/{{Xenosaga}}'' series strongly resembles this trope.
* ''VideoGame/SuperRobotWars'' is fond of busting this out whenever possible (including the ''Gundam'' and ''Evangelion'' examples above as well as many more from the mecha anime that take part). Examples in OriginalGeneration mechs include the Huckebein Boxer frame from ''Alpha'', the various Excellence frames from ''R'', and the G-Thundergate in ''Original Generation Gaiden''.
* Appears in ''VideoGame/ArmoredCore: For Answer'', after a fashion, with the VOB system, although the reasons are different.
** To explain, all Armored Cores have a special booster system called Over Boost, which lets the mech go really fast, but sometimes this isn't enough. The VOB stands for Vanguard Over Boost, and it basically amounts to a few Space Shuttle [=SRBs=] bolted together and duct-taped to the back of the AC for when they need to get into a combat area ''really goddamn fast''.
** The VOB's average speed is around 2500 kph. It's possible to build a mech that has a normal OB ''faster'' than that, and actually get slowed down by missions that require the VOB. Many optimized OB Lancer and Twin Blade builds can accomplish this with ease, especially when you turn on the [[GameBreaker Unlimited Energy Regulation]].
* ''VideoGame/AssaultSuitsValken'' had three [[UnexpectedGameplayChange shooter levels]] where the player's mecha is outfitted with a rocket pack.
* ''TabletopGame/{{Warhammer 40000}}'''':'' ''VideoGame/DawnOfWar'' '':'' ''[[ExpansionPack Dark Crusade]]'' -- Though used on [[PoweredArmor battlesuits]] and not HumongousMecha, the Tau Commander and Crisis suits can be further upgraded once built with different weapons (the jetpack needs to be researched elsewhere). In the campaign, the Commander gets a lot more upgrades, such as stealth and drones.
* ''VisualNovel/{{Demonbane}}'': The titular Demonbane later gain ''Shantak'' flight system.
* In ''VideoGame/ThunderForce V'', while not a mecha, the 5th mission start with your fighter RVR-01 Gauntlet docked with Brigandine module. It can take lot of hits as and has as unlimited SecondaryFire (one being WaveMotionGun) but is [[MightyGlacier huge and slow]]. Too bad that [[TooCoolToLive Brigandine only lasts for one stage]], but the Gauntlet will keep some upgrades from it and become RVR-02 Vambrace afterward.
** On enemy's side, the [[SuperPrototype Original]] [[EvilCounterpart Vasteel]] will fight you using its own modules, each one is larger and more bizzare than before . Then in ''VI'', Vasteel Nocht will upgrade itself after previously being blasted apart by having new parts added onto old ones before recombining.
** Also from ''VI'', the fight against Perfect Gargoyle start with its being serpent-like form, damage it enough, and the thing with combine with main body.
* ''VideoGame/{{Einhander}}'': Once [[ChickenWalker Sturmvogel]] takes enough damage, a flying armored unit will attach on top of it, allowing it to spam missiles and bombs.
* ''VideoGame/ShinSuperRobotWars'':
** The "Plus" parts for the R-2 Powered and the R-3 Powered.
** During a Space Route Scenario, Kouji and Astonage are both a tad baffled how to use whatever the new gadget on Mazinger Z is. It claims to be some type of energy charger, and doesn't have any visible controls. Astonage figures that it will probably just... do whatever it does when the time comes.
** The other Super Robots get mentioned upgrades off-screen.
* The Armored Command Units in both ''VideoGame/SupremeCommander'' titles and their buddies, the Support Armored Command Unit, are more or less built around being customizable to fit the commander's needs. They take the form new parts on the arms and as backpacks for the Commanders, ranging from just producing more resources to microwave lasers, nuclear missile launchers, and shields.
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[[folder:Western Animation]]
* The ''Franchise/{{Transformers}}'' franchise:
** Ultra Magnus, who debuted in ''WesternAnimation/TheTransformersTheMovie'', was the first example, as his toy was a recolored Optimus Prime cab with a transforming car-carrier trailer that became armor for the smaller robot. Although he was not depicted in this manner in the cartoon or original comics (simply transforming from truck to combined robot), the [[ComicBook/TransformersGenerationOne Dreamwave comics]] brought the concept into the fiction proper. Many subsequent G1 Ultra Magnus toys have just been Optimus Prime recolors without the additional trailer, and the lack of a "proper" Magnus for many years helped drive the third-party market to create their own trailer add-ons, most notably the "City Commander" set for Classics Ultra Magnus. The expansion pack aspect is averted with the ''Titanium'', MP-22 ''Masterpiece'', and ''Combiner Wars'' toys, although ''Combiner Wars'' Ultra Magnus adds a new wrinkle from the IDW comics, as "Ultra Magnus" is actually a LegacyCharacter, and the figure is essentially PoweredArmor for the diminutive Minimus Ambus.
** Beginning with Powermaster Optimus Prime, many versions of the Autobot leader have been depicted as combining with his trailer to create a larger robot and/or give him additional firepower. Powermaster Prime only appeared animated in commercials, though, and as a live-action mock-up in the host segments for the repackaged episodes of the original cartoon in the short-lived "season 5". His ''Anime/TransformersMasterforce'' counterpart, God Ginrai, included a second trailer which, when not combined with Super Ginrai, could function as a semi-autonomous drone named Godbomber.
** The [[Anime/TransformersHeadmasters Japanese Headmasters]] could be considered this as well, as the smaller "head" robots were the sentient components which combined with the larger non-sentient "transtector" bodies.
** Ultra Magnus himself became a MechaExpansionPack for Optimus in ''Car Robots/[[Anime/TransformersRobotsInDisguise Robots in Disguise]]''. However, it's a plot point that "Omega Prime" is under both their control at once: Ultra Magnus thinks he should be leader instead of his [[CainAndAbel brother]], but the Matrix of Leadership's full power must be unlocked by both together. When they become Omega Prime, this form even has its own voice actor, not Optimus's ''or'' Magnus's.
** The Anime/UnicronTrilogy heavily featured Transformers combining for power enhancements.
*** The whole plot of ''Anime/TransformersArmada'' centered around the Minicons, who by combining with larger Transformers (referred to as "bulks" by the Minicons) could unlock special powers and weapons. In addition, Optimus Prime could not only combine with his trailer again, but he could also instead combine with Jetfire to create the flight-capable Jet Optimus. And either of Prime's combined forms could additionally combine with Overload to give him a [[BFG huge pair of shoulder cannons]].
*** ''Anime/TransformersEnergon'' featured more "Powerlinking", taken to a new level. Unlike previous multi-Transformer [[CombiningMecha gestalts]] which were typically composed of five or six individual Transformers (although there were a few of those in this series as well), ''Energon'' featured Autobots combining in pairs, with the Autobot forming the top half being in full control, leaving the "bottom" Autobot essentially dormant. Optimus Prime could not combine in this manner in the series, although he had his own team of drone vehicles that could combine with him to form a super mode; Wing Saber could also separate into limb components to combine with Optimus in this manner. Prime could also combine with Omega Supreme (who himself was essentially a Headmaster in the Japanese style, with the tiny Omega robot controlling the larger body). There ''was'' a Powerlinx Optimus Prime toy released that could combine with other Powerlinx Autobots, though he never showed this ability in the anime (and due to Powerlinx Optimus being smaller, his combined form with the much larger Jetfire toy is... awkward, to say the least).
*** ''Anime/TransformersCybertron'' once again had Optimus Prime able to combine with his trailer, and he could also combine with Leobreaker, although this time the latter only formed a new arm for Optimus. Leobreaker's EvilCountepart, Nemesis Breaker, could do the same for Megatron.
** The second live-action movie, ''Film/TransformersRevengeOfTheFallen'', has Optimus combine with Jetfire again, with Jetfire turning into, basically, a jetpack.
** ''Film/TransformersDarkOfTheMoon'' has Optimus finally get a trailer. It's both a mobile armory and a flight pack. And it's awesome.
* Parodied in ''WesternAnimation/MegasXLR'', as with everything else. Coop [[AssShove shoves Megas' hands and feet up four of the S Force's "Zorps'" butts]], and slaps the bird Zorp on his back. It's called "the most foul attempt at military strategy [one S Force member] had ever seen".
[[/folder]]
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