World War X provides examples of the following tropes:
Tropes for all universes:
All Myths Are True: Given how many of the Greco-Roman, Basque, Norse, Slavic, Japanese, and Aztec Pantheons have shown up, as well as Angels, it's a safe bet that this is in effect.
Those Wacky Nazis: Played straight, subverted, and zig-zagged. Sometimes they are the hams of film, other times they are as coldly and hatefully evil as they were perceived in Real Life. Sometimes, they are just soldiers trying to get through a completely mad war. Depends on the character, and on which theatre they're on.
Hot Blooded: Most characters with a name are this, but in particular is the water fairy Rusalka, whose primary offensive abilities revolve around cold and ice.
No-Holds-Barred Beatdown: Wotan delivers one of these to Samyaza, after learning just who was powering Erzengel.
Our Angels Are Different: Samyaza rocks it Old Testament style. As do all of the other angels. Phanuel, for example, has six wings, metallic blue skin, has permanently closed eyes, no lower body, and a wheel covered in eyes where his waist would be. It gets weirder from there.
The Ophanim are even weirder. They are completely made up of wheels covered in eyes, can shoot flaming swords out of said eyes, and serves as a Clown Car Base for the smaller Virtues (which are androgynous crystalline Winged Humanoids).
The Blackwatch were, apparently, Fade's brothers, so he fits here.
Badass Normal: used (at first) by the Blackwatch, subverted by the Royal Marine squad under the command of Sergeant Lewis Rotham (who currently seem to be horribly outclassed by the gods waging war around them). They are, however, slowly recovering.
Bar Brawl: Having Heracles and Hercules drunk and bored is a bad idea (even though the WDM started it).
Bash Brothers: Hercules and Heracles appear to be shaping up to be this...
Biological Mashup: Scylla is an unholy melding of tentacles and dog heads that can eat a battleship in two bites.
Colossus Climb: Heracles subverts this by climbing up the Throne of Vulcan, with a little assistance... By which I mean strapping himself into a missile and firing himself up there.
Eye Scream: Cyclopes get shot or stabbed in the eyes a lot.
Full Frontal Assault: Fade has all his clothes burned away during a fight with Octavian, and spend the rest of the fight like this.
Handicapped Badass: Octavian loses an arm to the Wendigo, and due to the nature of the wound, won't be able to regrow it with nanites for a long time.
Samus Is a Girl: turns out that the Wendigo is a woman, and Fade's older sister.
Those Two Guys: Hercules and Heracles seem to be taking a break from fighting and commenting on the battle, mostly involving potshots at the other's pantheon.
Wendigo: It is summoned as a distraction by the Blackwatch. It can teleport, grows as it eats people, and is The Virus.
Why Won't You Die?: the Wendigo's ability to return from seemingly certain defeat ellicits this reaction from Octavian.
Your Mom: Several of these get thrown about by Heracles and Hercules.
Tropes for Japanese Spirit Warriors VS. The Raygun Gothic Allies:
Airborne Aircraft Carrier: The Sky Fortress Seiryuu for the Japanese, the HMAAS Triumph for the Allies.
Alien Geometries: The Aberration is a living, biological example.
Animal Mecha: The Sea Titan Genbu is a titanic sea turtle mecha.
Badass Santa: The Australians brought in Father Christmas to aid in the invasion of the Phillipines.
Baleful Polymorph: The Bunyip turns a large number of Japanese soldiers into black swans.
Combat Pragmatist: The Bushman has no qualms about running or using less honourable tactics against the things he fight. It's already saved his life at least once, and he's killed several of Shinshiro's personal guards and crippled a pair of warmechs using dishonourable tactics.
Establishing Character Moment: when we first see Shinshiro, he is drinking tea in his command center when two subordinates burst in, bearing important information concerning the battle. He then calmly beheads the man who interrupted his tea, explains why he did so to the second man, gives said man a chance to avoid making the same mistake, then invites him to have some tea and explain the situation.
Gundam Jack: The Engineer pilots a mecha made out of two Japanese mechas he stole. The Bushman is capable of using Pokeballs to a similar effect on the Youkai and even, at one point, another mecha.
Humans Through Alien Eyes: The Aberration sees us all as something just as horrific as we see it, and believed we were all out to torture and kill it, resulting in it's homicidal rampage.
Humongous Mecha: Liberty Prime and the turtle-shaped Sea Titan Genbu.
Hollywood Voodoo: possibly averted, given the number of Lwa that have appeared and the implication that Nwosu and possibly Pierre are practitioners of the Voudou faith.
King Kong: No really. Unleashed by the Nazis, though they weren't able to deploy it properly, so now it's attacking everything in sight.
Body Horror: The Technological Ascendancy Battalion.
Dem Bones: El Coronel's Mexican battalion, who are all brightly-painted Day Of The Dead-style skeletons.
Mayincatec: Appears to be averting this, as some of the players put in the research to get all of the facts straight regarding the Aztec Pantheon.
Human Sacrifice: It's the Aztecs, for crying out loud. In this particular case, someone needs to die to summon the Pantheon into their Physical God form, except for Xiuhcoatl, who comes as a bonus package for summoning Huitzilopochtli.
Shown Their Work: All of the dogfight- and aircraft-related terms used by Thunderchief, and to a lesser extent the Mudbugs.
Transforming Mecha: The Colossi Prototypes, which can transform from an aircraft into a mecha and back again.