Author's Saving Throw: Foreign gunpla builders ticked off by the price mark-ups and rarity of Premium Bandai model kits for people outside of Japan breathed a sigh of relief once it was announced that Premium Bandai's Gundam products would be coming to the West starting April in 2020.
The fandom is generally grouped roughly based on which series brought you into the fandom, though this has died way down since Gundam's heyday in the early 2000s. The original split was between UC purists and Wingers, with a smaller faction of Seedlings arising later. Gundam 00 was divisive due to its much more Super Robot-styled Gundams and the First Contact plot of the movie given that Absent Aliens has long been a hallmark of the franchise. A later series, Mobile Suit Gundam AGE, has caused some disagreements over its "kiddie" styling (to say nothing of the writing gaffes it suffered in its last two arcs).
"Space magic" elements not grounded in Minovsky Physics such as Newtypes and Psychoframes. Some fans accept them for being around as early as the first installment and find them to be part of the enjoyment of the franchise. Other fans feel that a Real Robot show should not have such elements and instead focus on grounded realism (at least as much realism as a Humongous Mecha show can have). Some have come to view it as something of a Franchise Original Sin due to it's presence leading to similar things being implemented in other series.
Which Mobile Suit in the series is the most powerful? There is a lot to argue over and it is perhaps one of the most common arguments in the fandom. And while a lot of people have their own take, most of the time it becomes a battle between Dark History Turn A, Crystallized Unicorn and ELS Quanta.
Go ahead and call the Mobile Suits "Transformers", we dare you. note It barely helped that Shōji Kawamori, the designer of the pre-Transformers Diaclone toyline, also designed Gundam-type Mobile Suits.
Be sure to learn that not all Mobile Suits are Gundams before getting into a discussion with fans, or risk ticking them off by calling suits like Zakus or BuCUEs Gundams.
Fanfic Fuel: Even the original Mobile Suit Gundam made it clear that what was shown on screen was simply one small part of a large war. The UC timeline spans over two centuries, and then there are the Alternate Universe series, and that's not even considering fans making their own Gundam AU. There's also less of an aversion to fans making up all-new casts due to the practice of introducing a new lead character for every anime, manga and video game.
Fanon: The fandom is quite good at creating it, given how many Alternate Continuity versions and contradictory source materials there are.
The "Space Magic" element is often a contentious topic with some feeling like it takes away from the Real Robot feel in many series. This is something that was first introduced in the very first show and subsequently escalated in the following series. The idea of Newtypes were considered groundbreaking at that time and the powers provided usually don't result in fantastical elements and/or Deus Ex Machinas that would make the audience feel like that they are watching a different show altogether, which allowed Newtypes to be mostly immune to the criticism later versions would suffer from. Not to mention, "Space Magic" was also used more often as time went on to justify plot holes and physics-defying feats, turning it into a writing crutch.
Proportionally speaking, the Master Grade line of model kits sells incredibly well in most foreign countries like Australia and the US. This was very likely due to the line's plethora of gimmicks, which consists of of inner frames (If you don't count even older ones), poseable fingers, excellent color separation (current kits), the usage of clear parts etc.
As a mecha franchise, Gundam was definitely a top show in Japan. However, it is basically the quintessential Japanese mecha anime in the eyes of the Western world. Think of 'Japanese mecha anime' and most English-speaking fandom would default to 'Gundam', whereas while respected in Japan, there is another anime that didn't fly that well in the Western market, but the Japanese still considered it more influential than Gundam when it comes to mecha anime: Mazinger Z.
I Am Not Shazam: At least you can find one of the franchise's (inexperienced) fandom referring the other non-Gundam-type Mobile Suits as the said titular name.
Just Here for Godzilla: Why some fans enjoy the franchise despite finding the plots boring and the characters irritating. It's still got giant robots blowing each other up!
Yes, the Federation has corrupt leaders. Yes, Zeon has many good, moral people who serve it. Yes, the Titans are bad. That being said, it's a little scary how many fans will knee-jerk a SIEG ZEON for a regime that murdered billions of people and continued to wipe out metropolitan centers every few years "for freedom".
Moment of Awesome: The 30th anniversary short "Gundam Perfect Mission", where the protagonist Gundams from every anime up through Unicorn work together to get the Core Fighter into space, where it forms into the original Gundam, the whole thing ending with a "YEAH!" Shot.
Rooting for the Empire: By the truckloads. For UC, Zeon has far more vocal fans than the Earth Federation. In CE, just mentioning it in reference to the Earth Alliance or ZAFT is likely to cause a Flame War over who was really the bad guy. Ditto, though to a lesser extent, for Mobile Suit Gundam 00. The same debate over whether Vagan or the Earth Federal Forces is worse in Gundam AGE is getting ugly as well. The same goes through Gundam Iron-Blooded Orphans where you got Tekkadan vs. Gjallarhorn (particularly in Season 2) debate.
Tough Act to Follow: Many fans view Tomino's work as this, with anything set in an Alternate Universe very rarely holding up to Tomino's standard. Shows set in Tomino's Universal Century have fared much better, with all of the OVAs (none of which had any input or involvement from Tomino) being highly rated by both fans and Tomino himself.
True Art Is Angsty: Zeta Gundam, while having one of the bleakest endings in all Gundam, is generally considered to be one of the best of them all. Gundam 0080 is similarly dark, and similarly exalted. On the other hand, ∀ Gundam is also considered to be among the best, and it's arguably the happiest Gundam series. Ditto for Mobile Suit Crossbone Gundam another series that avoids the Kill 'Em All status Tomino is infamous for. Incidentally, Tomino wrote Zeta, Turn A, and Crossbones. Gundam Build Fighters, which is orders of magnitude more lighthearted than anything else in the franchise, also got a very positive response.
Win Back the Crowd: After numerous failings, Gundam was completely pulled from US markets. However, the success of Mobile Suit Gundam: The Origin and Mobile Suit Gundam Unicorn overseas, combined with high ratings on official Gundam Build Fighters streams led to the franchise being picked up by Nozomi Entertainment, with a dub of the anime version of The Origin on the way. Gunpla has also been showing up at select Barnes and Noble retailers, and Bluefin opened up a Tamashii Web Shop in the US, with hopes for a Gunpla Shop. And as if to say "sorry" for leaving before ∀ Gundam could be released during Bandai Entertainment's run, it will be one of the first series to be released by Nozomi. Things are looking for a grand return...