"I love a lot of cartoon characters like Optimus Prime from The Transformers, Guyver and many more. But no one ever came close to Grendizer, I like Grendizer so much that I refuse to think of it as a cartoon. This show carried a lot of morals and emotions. Duke Fleed was a great character by all standards. He was a selfless loving person, even though he was bleeding of pain inside."
UFO Robot Grendizer (UFOロボ·グレンダイザー, UFO Robo Gurendaizā, sometimes romanized as UFO Robo Grendizer), known alternately by the names Grandizer, Goldorak and Goldrake, is a Super Robot GenreMecha Show anime and manga created by Go Nagai, and the final series in the Mazinger trilogy, (chronologically set after Mazinger Z and Great Mazinger). It was broadcast on Japanese television from October 5, 1975, to February 27, 1977, and lasted 74 episodes. Three manga versions were produced, one of them written by Go Nagai and the others by Gosaku Ota and Eiji Imamichi.Kouji Kabuto, hero of the the wars against Dr. Hell and the Mykene Empire, return to Japan after a short stay overseas and arrives at the Makiba Ranch to meet Prof. Umon and talk with him about the recent trend of ufo sightings in Japan. There he meets the Makiba family and Daisuke, Dr. Umon's son, who comes across like a weird, silent, lonely and taciturn boy. To add to the weirdness, when Kouji expresses his desire of being the one makes a First Contact with intelligent alien lifeforms, Daisuke warns him that he can not be sure of the aliens he intends meeting are friendly.Later, Kouji goes to meet an alien fleet that is hovering over the nearest city, but when he tries to communicate with them, he finds out... that no, they are not friendly. However he is rescued by an unknown Humongous Mecha that easily destroys the hostile fleet. Kouji right away suspects that Daisuke is the pilot. When he confronts Daisuke and Prof. Umon about it, they explain the next history.A while ago, the Vega homeworld became unstable and fell into ruin due to its inhabitants overmining and overexploitingVegatron, a powerful radioactive ore. Seeking finding another planet to settle on, King Vega's armies started attacking and conquering neighbor worlds, like planet Fleed, an highly advanced but peaceful and idyllic world. The Vegan Alliance easily succeeded on taking over the planet, but the Vegatron bombs that they used to annihilate the Fleedian army and cities turned the planet into an inhabitable radioactive wasteland.The Fleedian Royal Family got murdered, but Crown Prince Duke Fleed managed stealing Grendizer, a Humongous Mecha built by the Vegan army using planet Fleed's resources to spearhead their next conquests (or depending on the version, the embodiment of the Fleedian god of war that the Vegans had seized before the war broke out) and escaping. Grendizer guided him towards Earth, and Duke was found by Prof. Umon, who took him in like his son and assisted him in hiding Grendizer. Taking the identity of Daisuke Umon, Duke started working in the ranch and tried leading a normal life, forgetting his past.However the coming of the Vegan Alliance is about of putting an end to his peaceful life. Duke hates war and fighting, he likes his new life and he just wants to be normal, but if he does not fight his adoptive world will become another poisoned Crap Sack World. And if he ran and abandoned his home again cowardly he would be unable to stand it (he already got a pretty severe Heroic BSOD due to leaving Fleed).He ran away once. NEVER AGAIN.Grendizer was well-received in countries like France, Italy, Canada, the Middle East, Greece and Russia (but not in Japan, and in countries in which the previously two series were broadcasted first, due to the differences in concept and story). When it was shown in the US, it was Macekred into Grandizer as part of the Force Five syndication block. Two episodes of Grandizer were released on VHS in America; it is otherwise hard to get in the US.Character Sheet is now in construction.
Action-Hogging Opening: The openings of the trilogy feature more action -featuring the titular HumongousMechas tearing their way through an army of enemies-, and a better animation than an average episode of their series -especially of Grendizer-.
Adrenaline Makeover: As Hikaru decides to toughen up, her wardrobe changes from flowing dresses to miniskirts and boots.
Aerial Canyon Chase: Used in the last episode, when General Gandal (Minos) tries to ram his ship into Grendizer in a suicide attack. Duke Freed manages to make him crash into a cliff, since the Spazer (Grendizer's UFO) was still controllable, while Gandal's flagship was a flaming mess.
Airborne Aircraft Carrier: The Vegan Empire had a huge number of oval-shaped carriers to spearhead their inter-planetary conquest campaigns that were armed with missiles and laser beams and were used to store Saucer Beasts and Vega Beasts and mini-ufos. Some aircrafts belonging to several of the Co-Dragons were named, like Blaki's Motherburn, Minister Zuril's Warrior Mothership...
Alien Among Us: This is the initial premise: Duke and his sister Maria arrived at Earth running from his homeworld's destruction, and he chose living on our planet (he might leave at any time, but having no home to return to, he sees no point), pretending being a normal human. However, Kouji suspected he was not a normal person when he met him for first time, and playing his charade gets increasingly hard due to the VeganAllianceinvasion he has to fight, in such a way that the whole case know his real self after the first season. Finally, after the Grand Finale he and his sister return to planet Fleed to help to rebuild it.
Aliens Are Bastards: This trope is played with. At the start Kouji believes he can try to communicate with the aliens and befriend them, but Daisuke tries to warn him they are NOT his friends and are NOT peaceful or reasonable. However, Daisuke himself was an alien and a decent person. And although most of the Vegans at the beginning are portrayed like bastards -and the Mooks are Always Chaotic Evil-, along the series more aliens -including Vegans- are introduced who are decent people at best or at worst are Well Intentioned Extremists who believe that Utopia Justifies the Means.
Alpha Strike: In the climax of the first season's two-part finale Duke played chicken with the Mother Burn -Blackie's Cool Starship-, shooting all of Grendizer's weapons at once as he flied straight towards it. And he won!
Alternate Continuity: As things currently stand, Grendizer is the most powerful robot in the Mazinger universe... but so is the Mazinkaiser. This means that the two are mutually exclusive and aside from a single piece of promotional material, they have never appeared together in a fictional work, be it animation or a Super Robot Wars game. Go Nagai often jokes that he doesn't want to establish one as more powerful than the other and avoids having Grendizer and Mazinkaiser appear side by side for that reason. There have been rumors that he intends to clear this up at some point, but so far the two remain exclusive.
In UFO Robo Grendizer, Mazinger-Z, Great Mazinger and Grendizer combined all of their attacks in one manga scene to destroy a Vegan starship. And in one of the movies, Grendizer and Great Mazinger combined their Chest Blaster attacks to destroy a Saucer Beast.
The Super Robot Wars games have exploited this. When several of the Go Nagai mechas show up in the same game, they are given combination attacks. It is usually called Final Dynamic Special, and it is always impressive: .
Always Chaotic Evil: At the beginning it looks the trope is being played straight, but finaly it is averted. Several of the Vegans are decent people and many of them are given redeeming qualities.
Amnesia Danger: At the first episode of the Gosaku Ota manga, Duke does not remember anything about his past since Dr. Umon had wiped his memory's out so he could live peacefully without remembering anything about his destroyed home and slaughtered family. He got his memories back shortly after the Vegans attacked.
And This Is for...: It happens at least once in the manga penned by Go Nagai. After the Vegans kill one of his oldest friends, Duke rips to pieces a Saucer Beast as he yells: "And this is for my friend!"
Animal Mecha: Several Saucer Beasts resembled animals, mainly reptiles.
Bad Moon Rising: The Moon becoming red was a sign of the Vegan Alliance was getting ready another attack -and the main characters eventually learnt to watch for that-. One of the manga versions -penned by Gosaku Ota- reinforced that: in the first pages a red skull appeared on the Moon's surface (a sign of the Vegans had come) Duke felt upset when he saw it, and wondered if that was a bad omen.
Be Careful What You Wish For: Danbei Makiba (Hikaru's father) was obsessed with meeting aliens. He did not expect those aliens were hostile conquerors bent on taking over Earth. He didn't expect either that one of his employees was an alien, and his daughter would have fallen for him.
Berserk Button: Out of all pilots in the trilogy, Duke had the biggest Berserk Button. Nothing got his blood boiling like mentioning the Fleedian genocyde and the deaths of his family. And when a Vegan commander or soldier taunted him with it... let's tell it did not end up well for him.
And in the manga penned by Go Nagai, Kouji and Tetsuya. And in another chapter, Brunhild, an old friend of Duke. Nonetheless, he was aware enough to warn Duke against come closer and beg to kill him.
Card-Carrying Villain: Vega's homeworld was dying cause the overexploitation of a rare radioactive mineral called vegatron. Big Bad King Vega started his campaign of conquest through the galaxy because he needed to find a suitable world to settle their people on (and because he was a power-hungry bastard). His Co-Dragons followed him out of loyalty to him or to the Empire, and some of them were WellIntentionedExtremists, but Barados... Good Lord, Barados was pointlessly cruel and he committed atrocities as laughing: deliberately murdering women and children to exterminate a planet's population, taking hostages to blackmail his enemies with and then killing them in a horrible way... Let's tell than The Hero Duke told that was the only Vegan he could not forgive and when he died, no Vegan higher-up missed him.
Face Ship: When Grendizer combines with his flying device, its face shows up on the frontside.
Darkest Hour: In the finale of the first season, Duke was defeated and forced into hiding with Grendizer, Kouji was shot down, Hikaru was dying, the base was taken by Blackie and Professor Umon was tortured.
Dating Catwoman: Duke and Rubina. Although there was not much dating after the annihilation of Fleed.
Destructive Saviour: When Grendizer and the Vegans duke it out, the battlefield gets wasted. Duke tries to lead them away the cities, though, to prevent this.
Detachment Combat: All vehicles allowed Grendizer flying -or maneouvering more easily in sea or underground- were detachable and could attack separately.
The Determinator: Even though Duke is calmer and more focused than his predecessors and he actually was forced to run away once, he is not a quitter either. He has gone through battles where he was clearly losing but finally he pulled through due to effort, brains and guts and a downright refusal to lie down and die.
Dirty Coward: Emperor Vega tend to lose his coolness, get frightened and run away when someone is aiming a gun to his head.
Earth Is the Center of the Universe: Kind of subverted. The Vegans had conquered many other planets before striking Earth. It is true Duke Fleed landed on Earth -from all places!- when he ran away from the Vegan troops, and the Vegans show a special interest for Earth, but that is because there are not so many habitable worlds (Fridge Brilliance which is utterly true!). Earth, Fleed and Vega had a similar atmosphere and enviroment, so Earth was the kind of planet they were searching for.
Enemy Mine: Subverted. In one of the manga versions, Great MazingerBig Bad, Emperor of Darkness, offered Kouji Kabuto an alliance to fight the Vegans together. It was subverted because Kouji refused the offer and King Vega killed the Emperor to impede that alliance and get ridden of a possible enemy and competitor.
Everyone Can See It: Duke averted this trope with Hikaru and with Rubina. However, Kouji was absolutely oblivious to the feelings of Maria. Of course, he was the only one (much to Duke's amusement).
Evil Versus Evil: In the Gosaku Ota chapters, King Vega killed Emperor of Darkness, Big Bad of the former series (Great Mazinger). Pretty fun, King Vega not only did it because he was a potential competitor -since he also wanted to Take Over the World-, but also because Emperor of Darkness was wanting to ally with the heroes to overthrow him.
Executive Meddling: Go Nagai originally wanted Sayaka to be the 4th spazer pilot but was opposed by director and co-plotter of the series, Shingo Araki, who wanted and indeed did introduce his own character to the series, Maria.
Expository Theme Tune: "Come on, Come on, Duke Fleed! Fly, fly Grendizer! Across the land, the ocean and the blue sky! Joined for the peace, Keeping ourselves steady to protect everybody."
Faceless Goons: All Vegan soldiers wore a green-and-yellow uniform with cap-like helmets with yellow, round eyes and weird gill-like marks covered their whole faces and necks.
Falling into the Cockpit: Duke -and Hikaru- play it straight after a fashion (in the case of Duke, it depends on what version we are talking. In the Gosaku Ota episodes, Grendizer activated on its own to lead Duke far away from Fleed and save his life). Maria, on the other hand, was trained to pilot the Drill Spacer.
On the other hand, Kouji avoided the trope twice: Kouji tried to pilot Grendizer once during an emergency and he was unable. He stated the controls were too complicated to him. And in another ocassion he got to pilot Great Mazinger, and he was worried he would have forgotten how handling it. Fortunately, Great Mazinger controls were pretty similar to Mazinger's and he got several years worth of experience for that time.
Fantastic Nuke: The Vegatron bombs. Capable to obliterate whole cities, and left the land polluted with radioactivity afterwards.
Final Battle: It varies depending on if we are discussing the Go Nagai manga, the anime series or the Gosaku Ota manga. In the anime version, after his daughter got murdered, King Vega decided he had got it: he had wasted military resources trying take over Earth as planet Vega imploded and everyting he had managed was using up their resources, running out of Robeasts, and losing his commanders, his best soldiers and his daughter. So he ordered his troops to destroy their Space Base to hammer in them the idea of they now had no choice but conquering Earth or die, and he launched a full attack with the remnants of his army. Meanwhile, Duke took off in Grendizer and Kouji, Hikaru and Maria on a new starship. Both sides fought in the space, between Earth and Moon. The Vegan army was finally destroyed in the final confrontation, and Duke killed King Vega.Go Nagai manga version had no a definite ending, but Gosaku Ota version did it, and the final was very different from the anime series. Let's tell it got The End of the World as We Know It worse.
Giant Equals Invincible: Sort of. Vegan Robeasts could not be damaged by conventional weaponry, but neither did tinier Vegan combat ships. So it can be argued alien technology rather than sheer size was the cause of its invincibility.
Grand Finale: After his daughter's death, Big Bad King Vega has lost his patience and decides deploying all of his remaining troops to launch a final attack. Gandal dissuades him, though, and challenges Grendizer to a mecha duel. When he loses, one of his personalities realizes Grendizer is invincible and plans killing King Vega to negotiate peace with Earth separately, but the dominant personality executes her by attempting to commit high treason, and tries to kill Duke Fleed with a kamikaze attack. When he fails, King Vega decides invading Earth, destroying his Space Base to show his troops there's no turning back. Meanwhile, the four heroes take off towards the space to fight the Final Battle, using Grendizer and a new Cool Starship. Both fleets clash among Earth and Moon. After a long fight, Duke and his friends manage to win. Unfortunately it also means he and his sister will have to bid farewell to their friends and return to his homeworld. In one of the manga versions, Vegans' final attack caused the End of the World as We Know It.
Gut Punch: In the Ota chapters both sides loses the war. The Vegan invaders are destroyed, but Duke, Maria and Sayaka die and The End of the World as We Know It happens. Only Kouji and Hikaru are left alive. It was lucky Grendizer was the last series in the original saga, because you get to wonder how the creators could have gone one.
Heel-Face Turn: The female side of Gandal, a Vegan with two personalities and faces decided turning on the Emperor after realizing they would never defeat Grendizer.
Heel-Face Revolving Door: But then the male side took control back and shot himself/herself on the grounds of high treason.
Hoist by His Own Petard: The Vegans managed to make huge technological breakthroughs by exploiting ores of the material radioactive known as Vegatron. However, it led to his planet becoming unstable, forcing them to find new worlds to colonize. The vegatron bombs they rained upon Fleed scorched the Fleedian army to ashes, but they also turned the planet they intended to colonize on a radioactive wasteland. And finally, Vegatron radiation destroyed their homeworld and rendered their Moon Space Base -their last safe haven- inhabitable.
Hope Spot: In second-to-last episode, Rubina finds out her fiancé Duke Fleed is alive and flies to Earth to meet him. She apologises for the crimes her father committed and tries to convince him everybody -both Vegans and Earth's inhabitants- shall die if the war continues, and the only way to prevent it is they getting married and talking her father into moving the Vega folk to Fleed. And he accepts. For a moment it seems like if the war is over, but a Vegan squad was using Rubina like an unwitting bait attacks Duke. Rubina herself dies shortly after, destroying any hope of the conflict would end up peacefully and without one side annihilating the another one.
Human Aliens: The Fleedian race -mainly represented in the series by Duke and his sister Maria- look completely human. On the other hand, the aspect of the Vegans varies wildly. Emperor Vega seemed a hairy, pointy-eared, pig-nosed monster, but his daughter Rubina mostly seemed human. Other alien races in this universe range of monster-like to human-looking but with unusual hair, skin or/and eyes colour (like secondary character Menao).
I Am Who?: Maria got this reaction after her grandfather revealed she was not his granddaughter but an alien princess.
I Control My Minions Through...: King Vega used Authority (he was his planet's ruler), Loyalty (his minions were very loyal), Fear and Acceptance (he was a bastard, but he cared for his people. He started his conquering campaigns to find a new homeworld for them).
Interspecies Romance: The Mazinger trilogy has several examples from romances between humans and humanoid aliens: Duke and Hikaru, and Kouji and Maria. And the you have Duke and Rubina. Both of them are aliens but they are from different species -and born in different planets-.
It's Personal: In the Go Nagai manga, Commander Barendos dropped Duke's little siblings from a height from three kilometers. In front of Duke. Duke is usually calmed when he is not piloting, but the only sight or mention of Barendos is enough to press Duke's Berserk Button.
Japanese Ranguage: This trope affected the main character, Duke Fleed, whose name was written like "Dyūku Furīdo". Several of his enemies also suffered from it: "Blackie" was written "Burakki", and Gandal was turned into Gandar.
Jet Pack: Grendizer had THREE of them (not counting its spaceship): Double Spacer -to fly inside and outside of atmosphere-, Marine Spacer -to fly and dive underwater- and Drill Spacer -to fly and burrow underground-.
Jumped at the Call: Duke subverts it slightly. He was a reluctant hero hated fighting and just wanted being normal. When the Vegans attacked he could have remained lying low and nobody would have him forced to battle. He willingly decided fight, nonetheless (knowing the consequences of not acting are your new home will become an uninhabitable radioactive wasteland all people you care for will be dead or enslaved no doubt helped factored into his decision).
Love Dodecahedron: Hikaru is in love with Duke. Duke may reciprocate her feelings. Rubina is in love with him. Duke certainly reciprocates her feelings. And Minister Zuril was in love with Rubina. It is even more complicated if you think about Kouji and Maria and add Sayaka to the mix.
Luke, I Am Your Father: It was inverted and played straight. Maria told Duke she was daughter of the King and Queen of Fleed, not knowing he was their son, and therefore, her brother. The moment they played this trope straight with each other was definitely a Crowning Moment of Heartwarming.
Luminescent Blush: In one manga chapter, Hikaru bluntly told Duke she was interested in him. And Duke's face turned fully red!
Made of Indestructium: Grendizer was made with Gren, an incredibly tough metal. Nevertheless, it could not be found on Earth, so when Grendizer got damaged, he was repaired with Alloy Z.
The Man Behind the Man: In the original manga, Blackie is the first Vegan commander to show up, and he seems to be behind the invasion. However, in the next chapter, the Big Bad King Vega and his Dragon-in-Chief Gandal (commander of the armies tasked with the invasion) are introduced.
An even bigger problem, however, lies in the fact Koji's name was changed in a lot of foreign versions (for example, in France and Italy where Grendizer was absurdly huge, Koji was called "Alcor" after the star in Grendizer) and then got his normal, unmodified name back in other Mazinger works that aired after Grendizer was huge. These being the pre-Internet days, people didn't pick up on the fact that it was supposed to be the same character and so audiences assumed that Mazinger was simply a very blatant, cheap knockoff of Grendizer.
Mid-Season Upgrade: Grendizer got upgraded throughout the series with several attachable, flying vehicles allowed it maneouvering more easily in space, in sea or underground: Double Spacer -piloted by Kouji-, Marine Spacer -piloted by Hikaru- and Drill Spacer -piloted by Maria-.
Mind-Control Eyes: Not permanent when victims are brainwashed but sometimes can briefly have them.
Missing Mom: Duke and Maria's fathers got murdered before the sereis began. Hikaru and her brother's mother passed away, and they raised by their father exclusively.
Mission Control: Duke and his partners were assisted by the Prof. Umon and the Bridge Bunnies of the Space Science Laboratory, that provide plenty information and suggested strategies when they battled.
Near Villain Victory: One of the best examples happened in the two-part finale of the first season. Grendizer had been beaten by two Robeasts and forced to hiding, Kouji's TFO had been badly damaged, Blackie had taken control of the Science Space Center and tortured Dr. Umon. When Duke returned, he managed beat both mechas, saving his friends and destroying Blackie's command ship.
No Ending: The manga ends with a duel between Duke and one of the Vegans generals. Kouji got a minor moment of action, but Rubina and Maria had not been even mentioned, Hikaru was still in her pre-Action Girl days, Spazers hadn't been introduced, and there wasn't even a single instance of the Antigravity Storm attack.
Nuclear Weapons Taboo: Vegatron bombs. It is explicitly stated they are radioactive, they are able to easily obliterate whole cities, the explosion forms a mushroom cloud, and they leave the land polluted with radioactivity. But no, they are not nukes. They are vegatron bombs.
Obviously Evil: The decent or with more redeeming traits aliens are human-looking. The aliens who are more monstruous are pretty much bastards.
Pair the Spares: It's revealed in an episode that Koji loves Hikaru. But she loves Duke.So he decides to forget her.In the very next episode, Maria Grace arrives, and is soon attracted by Koji.
Papa Wolf: Danbei Makiba. He is fiercely protective of his daughter, constantly menacing with shooting the brains off of whoever ever thinks about damaging her or hurting in some way, shape or form. And God helps you if he entrusts Hikaru to you, and she doesn't remain perfectly safe and sound.
Pietà Plagiarism: It happened near from the end, when Rubina got murdered and Duke held her as she died.
Reforged into a Minion: The Vegans grafted brains of prisoners into their Saucer Beasts. Duke got a severe Heroic BSOD when he was told he technically had killed one friend of his every time he blew up a Robeast.
Power Fist: Several triangular blades are attached to the wrists of the Humongous Mecha, and bent towards the elbow. When Duke shoots a Rocket Punch, the blades turn forward and shred their target.
Hand Blast: Grendizer's backhands shot energy beams.
Rubber-Forehead Aliens: Vegans and other alien races have strangely-shaped heads or unusual skin or hair colours at the very least. Gandal has blue skin and his head looks cubic due to his very angular features, his wide forehead, and that the top of his head is nearly flat. Blackie has dark-purple skin, pointy ears and a very pointy, hairless head. Even the most human-looking aliens -like Rubina- have bluish or anormally pale skin, black irises or green or aquamarine hair (keep in mind no human character in this anime is blue-haired).
Rule of Three: It was not so blatant like in the first series. Still, Prof. Umon was assisted in the Lab by three Bridge Bunnies (Hayashi, Yamada and Aoi). Makiba family was formed by three members: Hikaru, Danbei and Goro. Duke battle partners were Kouji, Hikaru and his sister Maria. Grendizer got three MidSeason Upgrades: Double, Marine and Drill Spacer...
Sadistic Choice: It happened fairly often, especially in the manga penned by Go Nagai. In one chapter Duke gets attacked by one of his oldest friends, whom he believed dead but was being mind-controlled by the Vegans. His friend could not control his body but he still could warn Duke stay away from him... and beg kill him.
Shiny-Looking Spaceships: Both Grendizer and the Vegan starships are shiny-looking, bright and very polished -although they may get dirty in battle, though-.
Kouji / Hikaru: In one episode it was told Kouji was infatuated with Hikaru but he never tried anything with her out of respect for his friend Duke. Cue Maria showing up in the next episode (and keep in mind it was Sayaka who was meant to show up instead of her).
Duke / Hikaru and Kouji / Maria: Both pairings kind of sunk at the end of the series when Duke and Maria left Earth, forcing themselves to leave their friends behind for the sake of rebuilding their homeworld.
Starcrossed Lovers:Duke and Hikaru. Hikaru's father refused accepting their relationship (on grounds of Duke being male. Danbei was an Overprotective Dad was perfectly willing to kill any male came near from his daughter), but that was not the real obstacle (or an obstacle for that matter). The real obstacle was Duke wanted to return his planet to rebuild it if he managed surviving the war, whereas Hikaru did not want to leave Earth. Not matter what their feelings are, a separation is inevitable. Also, Duke and Rubina. Rubina is King Vega's daughter. They got engaged before the Fleed's invasion, but King Vega -who never agreed the engagement in first place-, refuses seeing his daughter getting married with Duke. Of course,it ended up in tears.
Stealth in Space: King Vega's tactic during his army's offensive final depended on being stealth. Of course, it did not work.
Super Robot Wars: Out of the trilogy this series has appeared the least but nevertheless has appeared a few times (2, 3, 4, EX, Compact 2, Impact, 64, Advance, Destiny, MX, and the first Z game). Rumor had it that Grendizer appears the least due to Go Nagai not wanting Mazinkaiser (which was created for the games and appears in many installments) or Grendizer to be shown as superior to one another in any way, but the SRW staff has said that there isn't an specific reason keeping the two series from appearing together. They simply just haven't decided to use them together yet.
Super Villain Lair: The lair of the Vegan invaders was a Space Base set in the Moon. When the Emperor began his final offensive against Earth, he ordered blowing it up to show his troops they had only two choices left: conquering Earth or die.
Tagalong Kid: Goro, Hikaru Makiba's little brother. Hikaru finds him very irritating.
Take Over the World: Planet Vega had become unstable due to the overexploitation of ores of vegatron, a highly radioactive material. King Vega needed to find another world to settle his people on, and so he began conquering other worlds. That expansionist campaign finally led them to Earth.
Taking the Bullet: During an aerial duel between Grendizer and another starship in the episode 72, Rubina flies her own ship between Grendizer and an energy beam to save Duke. She dies shortly after. Her  is done more tragic because Duke had accused her from betraying him shortly before. The whole episode was a Tear Jerker.
Techno Babble: Of course, being a sci-fi Humongous MechaMecha Show, instances of are plenty. An episode of the first season gave us a good example. The Vegans plot attacking during an eclipse and luring Duke to fight in the eclipse's umbra because the lack of solar waves will disrupt the flow of the Applied Phlebotinum that fuels Grendizer. Hence the Humongous Mecha will run out of power and will be rendered defenseless.
Telescoping Robot: Grendizer had one scythe stored into each shoulder could be joined to shape a double-edged shaft. The blades also worked like a Precision-Guided Boomerang. And that is not counting all weapons hid into its flying device.
10-Minute Retirement: DukeFleed was doing this at the beginning of the series. He was planet Fleed's Crown Prince. After VeganAlliance invaded his homeworld, murdered his family but his little sister, decimated his planet's army and turned the place into a radioactive wasteland, he ran away and settled on Earth, planning leading a peaceful life like a farmer and trying to ferget what happened. Then the Vegans Alliance found Earth, a friend of his was in danger, and he started his Super Robot and marched to the battle again.
This Is Unforgivable: Uttered by Duke when he remembered an unpleasant memory from the invasion and destruction of Fleed or when the Vegans had got him REAL pissed off. In the second instance you really did NOT want being the focus of his anger.
Tokyo Is the Center of the Universe: Subversion enforced. To start with, the Headquarters of the good guys is not in Tokyo but in the vicinity of Mount Fuji. Therefore, the enemy feels aren't compelled to exclusively target and attack Tokyo. Not only are a lot of Japanese cities destroyed but also the Vegan army attacked many countries, not only Japan.
Tomato in the Mirror: Maria Grace believed she was an average girl... until her gradnfather revealed that she was an alien.
And her brother Duke Fleed played this trope in the Gosaku Ota manga continuity. Dr. Umon had wiped out his memories so they did not torture him and he was able living like a normal human being. However, when a stream of reports of ufo sightings started to arriving to the Space Research Laboratory he started to feel odder and uneasier, although he did not udnderstand why. It was when the Vegans started to strike nearby cities he finally remembered he was an alien.
Tomboy and Girly Girl: Hikaru and Maria subvert the trope. Hikaru usually wears male clothes and is a Girly Girl. Maria, on the other hand, constantly and consistently wears dresses and skirts, and is a tomboy and a Biker Babe. Not matter what, they are good friends.
Too Good for This Sinful Earth: Several characters. The more prominent of them was Rubina. She was a good person sincerely loved Duke, and wanted reuniting with him to end up the war and rebuilding his planet together. Unfortunately, when she managed meeting Duke to talk with him, one of the Vegan generals took that chance to ambush Duke, and she died shilelding her fiancee from a shot.
True Blue Femininity: Hikaru is femenine, gentle and caring and wore a blue uniform. On contrast, Maria was a tomboyish Tsundere and usually wore red or pink.
Two-Faced: Lord/Lady Gandal is a BaronAshuraExpy with two personalities, a male one and a female one. During the first season, his body was male, but when the female side wanted taking control, his face split in two halves, revealing a tiny female human inside the head. Afterwards, his face changed every time he switched personalities. Due to their different personalities he combined being The Dragon with being The Starscream.
Ungrateful Bastard: In all series of the Mazinger trilogy, humans barely need a little push to side with or become puppets of the people who want to enslave them or annihilate them and turn on the people who are protecting them with their lives.
Unobtainium: Grendizer is built with an alien metal called Gren. Since it can not be found on Earth, when Grendizer gets damaged, Alloy Z is used to repair it.
Vegatron is a highly radioactive material only can be mined from planet Vega. The Vegans used it to create powerful weapons, but its overexploitation led to the planet becoming highly unstable.
Unrobotic Reveal: A variant. It is revealed that the Robeastsare powered by brains of Fleedian people. When Duke Fleed got told all Saucer Beasts he had been destroying contained all what was left of his family and friends, he got a Heroic BSOD.
Unusual Weapon Mounting: Grendizer's horns can unleash electrical discharges, its backhands shot laser rays, blades are stored into its shoulders that can be merged to form a double-headed scythe...
Use Your Head: Duke uses this tactic sometimes, although he has a good excuse: usually he is trying to ram the enemy rather head-butt it, but his Humongous Mecha head is on the front of his starship when both mechas combine, so that it is the first thing hits the enemy.
Walking Spoiler: Maria Grace Fleed. Her full name is already a total spoiler itself. Also Princess Rubina of Vega, fiancée to Duke.
War Is Hell: The message is core to the series and it is delivered in a pretty heavy-handed way. The Vegans tried to take over Fleed to settle on it but their own weapons turned the planet into an inhabitable, radioactive chunk of rock. The only thing their expansionist war achieved was the destruction of several planets and their own annihilation. The war scenes were depicted in a very harsh fashion. And several characters argued nothing could be gained from that conflict:
Hikaru: “Why friends must fight each other? It’s all the same. It doesn’t matter who wins… There’s no way peace can result from this fight!”
Rubina: "If this war continues, not only all Vegans but also Earth will be destroyed."
"Well Done, Son" Guy: Subverted. Minister Zuril had a son was obsessed with proving his worth to his father, even jeopardizing his life. However, Zuril was proud of him and tried to make him aware of that fact and he did not want him risking his life. Unfortunately, his son did not listen. He kept being obsessed with earning his father's approval, and finally he commited a Heroic Sacrifice to save his father's life. Zuril became very cold and fatalistic because it.
The Worf Effect: Kouji Kabuto had been The Hero for two Humongous Mecha series, facing dozens of enemies and -often- emerging victorious. In the first episode he got shot down easily by Vegan mini-ufos, forcing Duke to reveal his true identity to rescue him. Kouji got subjected to this trope throughout the whole series.
You Killed My Father: The parents and whole family of Duke and Maria got murdered by the Vegans. It is one of the resons because they want defeating them.