Even though I have given a detailed analysis of Grendizer as a distinct super robot, many Mazinger fans still don't (want to) understand why Grendizer is the most powerful super robot.  This section that I have added here will give you more detail and more clarification.  Let's start with something we can relate to, UFO Robo Grendizer vs. Great Mazinger, since we witnessed the two super robots square off against each other already.

Rationale 1. : Not really guys.  Grendizer was being double teamed by Great Mazinger and a Vegan saucer beast most of the time in that battle.  Grendizer was hit by Great Mazinger's Mazinger Blade and Thunder Break, but Grendizer wasn't scratched.  It was clearly an unfair match, but even then, Grendizer did extremely well and endured a lot of hits.

Rationale 2. : Absolutely not.  In the first encounter when Grendizer knocked the Mazinger Blade out of Great Mazinger's hands, Grendizer kind of paused for a second before being attacked from behind by the Vegan saucer beast.  If Duke Freed really wanted to destroy Great Mazinger then he would not have paused, on the contrary, he would've kept on attacking and may be slashed Great Mazinger's head off with the Double Harken, it doesn't take much guys.  Great Mazinger is more fragile than you think, don't forget the many times Great Mazinger came out of its own battles in its own series with no limbs left.

Another interesting point here is that Duke Freed shot Grendizer out of Spazer to attack Great Mazinger only after Captain Barendos launched the Navel Missiles from Great Mazinger at Grendizer.  Duke Freed obviously wasn't interested in fighting another good super robot.  This is Duke Freed guys, he's not obsessed about his machine Grendizer the way other pilots are obsessed about their machines.

Contrary to Great Mazinger giving Grendizer a taste of its weapons in that movie, Grendizer did not give Great Mazinger a taste of its weapons.  Grendizer got slashed a number of times with the Mazinger Blades, no effect.  Grendizer was hit with the Great Typhoon, no problem.  Grendizer was hit with the Thunder Break, still no effect.  Did Grendizer fire the Space Thunder at Great Mazinger?  Nop.  Did Grendizer hit Great Mazinger with the Double Harken?  Nop.  If the Double Harken came swinging at Great Mazinger, I think we would see either a head or a limb fly off.

Rationale 3. : Mazinger Z is way out, don't even go there.  Great Mazinger is not comparable with Grendizer either.  Sure, the Mazingers can try to fight Vegan enemies, but almost every time they will be back in the repair shop as a result of the damage they will suffer.  Look at how the Mazingers suffered damage in their own series by their own enemies.  You're telling me that they can take the more dangerous army of the united Vegan forces?

Think about it, if it was of any benefit or interest for Koji Kabuto to use a Mazinger then why didn't he do it in Grendizer?  Obviously he knew better not to.  Grendizer is the UFO robot that will fight the alien invaders of Vega, that's it.  Don't forget how at the end of the Great Mazinger series Koji Kabuto returned and launched Mazinger Z to help Tetsuya and Great Mazinger.  That was pretty good and I really enjoyed the teamwork there.  However, Koji Kabuto didn't do the same in the Grendizer series even though he could've if he really saw it as being feasible.

Another interesting point is Grendizer's flying ability as a UFO robot.  Grendizer when in Spazer is very swift and so it is able to out-fly and out-maneuver the Vegan UFO saucer beasts.  These saucer beasts fly at extremely fast speeds and are very difficult to beat in air battles.  They will fly rings around Great Mazinger even though Great Mazinger can fly.  Grendizer on the other hand will knock them out of the air and on the ground, then, Grendizer will "Shoot Out" of Spazer for the fight on land.  Grendizer is not able to fly as a robot, but it is able to float in the air.

Rationale 4. : Wrong again.  This has absolutely nothing to do with who's stronger or not.  Everyone needs help because nobody is invincible (except God of course).  Koji Kabuto and Duke Freed did some great teamwork together in that movie, that's all this means.

Rationale 5. : If you want to know what's up then you look at the actual stories of these super robots, that being the animations themselves and this is where the story comes to life in the way we should perceive it.  To me, other things like comics or mangas revolve around the real thing which is the actual animated series.  Comics and games as you can understand are not as authentic as the story in the animation itself.

Just to add to that, it is worth mentioning that Grendizer in the Super Robots Wars games is one of the top fighters in its ability to endure and dish out damage.  But even then, I don't take these non-animation items to make final judgments.

Rationale 6. : Who?  Mazin what?  Mazinkaiser, Great Mazinger, and Mazinger Z are all in their own Mazinger league.  Grendizer is a whole different ball game and there is no room to compare here.  Grendizer is a UFO robot that was built using the entire technology and resources of a very scientifically advanced planet for the purpose of taking over the universe.  Grendizer was not built in someone's basement the way Mazinger Z was, think about that.

Rationale 7. : No way.  Recall for a second here.  After all of the other super robots were defeated by Ankoku Daishogun (including the busted up Great Mazinger), Shin Getter Robo came out and attacked with his big axe weapon, then Grendizer came out and finished off Ankoku Daishogun with the Double Harken after saving Aphrodite A.  I repeat, Grendizer is the one that finished off Ankoku Daishogun, this should tell you something.  Then, the big fire enemy creature comes out to confront Grendizer and Shin Getter Robo who are both still standing.

After that, we are introduced to the newest Mazinger, that being Mazinkaiser.  Mazinkaiser shows up and the clip ends.  Now tell me, if this clip were to continue, wouldn't you see Grendizer, Shin Getter Robo, and Mazinkaiser teaming together as one team to fight the big fire enemy creature together?  These three super robots were all there undamaged, with the exception that Grendizer lost its Double Harken weapon when used to destroy Ankoku Daishogun.  This happened as a result of the big fire enemy creature coming out and burning everything in that area.

The indication given here at best is that these three super robots are in the same rank perhaps.  However, this in no way tells me that Mazinkaiser is any more powerful than Grendizer.  At best, and I repeat at best, they would be around the same strength, but even that possibility to me is not realistic when looking at Grendizer's storyline.

• THE STORYLINE GUYS, THE STORYLINE !!!  I mean what is more amazing than a super robot born through an entire civilization's science resources so it can be used to plunder the entire universe???  All this civilization did was devote all of its efforts to science and technology, it doesn't get any more powerful than that.
• GETTING TECHNICAL?  Although I don't remember where to get such information, but if one were to look at Grendizer's weight, metal, running speed, etc. as compared with Great Mazinger, it will be very clear that Grendizer is far more superior.  I know there are albums out there that give us this information, I have seen some information on other web-sites out there.
• THE DEATH BATTLE, BATTLE OF THE CENTURY.  Grendizer is not just a stand-alone super robot.  Let's not forget about Spazer which if used by Grendizer properly will enable Grendizer to win in any battle.  Spazer as a (huge) ship if used as a last resort can fly at full speed at Mazinkaiser and tear Mazinkaiser apart, or at least take Mazinkaiser down for the final blow.  Had enough yet?  But I don't think Grendizer will even need to do that to beat Mazinkaiser.
• I guess the best one to ask about this is GO NAGAI himself.  If Go Nagai can tell us that Mazinkaiser is more powerful than Grendizer, then I would be convinced.  But I won't be convinced about Mazinkaiser's ability to fight the Vegan saucer beasts the way Grendizer can because they are UFO's and only Grendizer the UFO Robot can confront them.