Humongous Mecha can be rather awesome on screen, but for a variety of reasons they would be impractical in real life. Strategically, a tall humanoid figure would be an easy target for missiles, even dumb artillery. Physically, they'd run into the Square-Cube Law at a great enough size. So, the Real Robot Genre often tries to include some manner of Applied Phlebotinum that would make building-sized robots more reasonable.
See Motion Capture Mecha for one of the more common techs. While the trope namer for Minovsky Physics was an example, not all examples of Mecha-Enabling Phlebotinum need be be so developed as to qualify for that trope. Many examples are very loosely science fictional, or even explicitly magic.
- Most iterations of the Gundam franchise include Minovsky Particles that interfere with radar, forcing combat to close ranges where mech agility makes them ideal, at minimum. Some also allow non-aerodynamic machines to fly.
- Neon Genesis Evangelion: The resident Kaiju have force fields that can soak nukes, so the Eva project developed cloned Angels with cockpits in their spines and bolted on enough armor to make them look like mecha.
- Tengen Toppa Gurren Lagann: Mechs run on the heroes' Spiral Energy rather than the laws of physics — in the setting, Awesomeness Is a Force that can manifest galaxy-sized robots in sufficient concentrations.
- The Code Geass setting's advanced technology is all explained by the mineral sakuradite. As a radioactive material and room-temperature superconductor, it's used as both the fuel source and power grid for the Knightmare Frames.
- Eureka Seven's mecha run on transparent light particles or 'trapars', which are particulates produced by the Scrub Coral that act like wave currents.
- In Robotech, the setting's Transforming Mecha are explicitly based on the reverse-engineered technology of the SDF-1, the emponymous robotech. It has something to do with a magic flower that can be burned for near-limitless energy and warp spacetime (and be chewed to get high).
- Cannon God Exaxxion: The Humongous Mecha in this manga rely entirely on gravitational control to function, or even stand. The square-cube law is addressed and without said gravitational control, the mecha would buckle under their own weight. In-Universe, the gravity controlling technology is incredibly energy consuming so there is another unobtanium energy source in the form of Dark Matter. Despite using an older-model robot, the titular mecha is so powerful because the heroes have a much larger store of Dark Matter, thus can use it more freely.
- The Vision of Escaflowne: Mechs, including the title one, run on petrified hearts of dead dragons.
- Defied in Stellvia of the Universe: There is no practical reason why the Infinity spaceship should be humanoid in shape. However, since it is given the center stage in humanity's greatest achievement, the Great Mission, its engineers decide to sink the extra costs into making it look like a human for the sheer symbolic value of it.
- Full Metal Panic! doesn't give any specific explanation for the show's standard-sized (~10 meters tall) mecha, but the Behemoth, a much larger one, is only able to support its weight thanks to a Lambda Driver propping it up.
- Pacific Rim partially accounts for the speed and reflexes of its Humongous Mecha by explaining that it requires two pilots to share the neural load through a mind-sharing mechanism known as the Drift. How they were able to build the mechs in the first place isn't elaborated on, but Fanon has concluded that the dead kaiju bodies were used in some way.
- Transformers Film Series;
- Transformers are created in the first place by a MacGuffin called the All-Spark. An alien device of unknown origin that can turn any machine into a Transforming Mecha.
- According to The Official Movie Guide, Protoforms are made up of densely packed Nanomachines. This is the semi-official Hand Wave for any transformation "cheats" in the films and where, for example, the rubber for Optimus' tires comes from.
- Transformers: Age of Extinction says that the franchise's Transforming Mecha are all made from a programmable metal called Transformium.
- Tony Stark uses a miniature generator in his chest called the Arc Reactor to power his Iron Man Powered Armor. Later versions of the armor had Arc Reactors built-in.
- In BattleTech, 'mechs depend on an artificial muscle tissue made from smart plastics called "myomer". Myomer is vastly more energy-efficient at converting reactor output into mechanical force than a conventional engine, letting 'mechs carry disproportionately heavier armour and weaponry at the same tonnage as a tracked vehicle while still being faster and more mobile. "Neurohelmets" use the pilot's own proprioception to keep the 'mech balanced. The square-cube law is still in effect but vastly reduced: 20 to 100 metric tons is the practical mass range for a battlemech, and heavier 100+ ton prototype designs tend to collapse under their own weight or simply sink into the ground. Powered Armor uses the same high-capacity power packs that make the series' man-portable laser rifles practical, allowing the armor to remain powered for hours without having to lug around a bulky engine.
- In Stars Without Number, mechs prove an ideal platform for ground-based quantum chaff systems, shielding entire platoons from nukes and guided missiles.
- Warhammer 40,000:
- The Eldar use mechs of varying sizes constructed from wraithbone, a psychically reactive plastic. The humanoid form makes it easier for the pilot and/or the soul-stone controlling the machine to link with it and use it as if it were their own body.
- The Titans used by the Imperium use a similar, though cruder neural interface, but they're mainly humanoid for propaganda reasons, showing the Imperium's reverence for the "holy human form".
- Orky "Stompas" only avoid collapsing under their own weight thanks to the Orkz' gestalt psychic field, much like the rest of their technology. Although oddly enough, the stompas' bottom-heavy design makes them the most plausible of the setting's giant battlemechs.
- While the Tau make heavy use of Mini-Mecha but dismissed reports of the Imperium's walking cathedrals as "ridiculous" until encountering them in the Damocles Crusade, at which point they started countering them with heavy bombers before grudgingly designing their own Titans.
- Nearly all Titans are fitted with Void Shields or the equivalent, mitigating some of the "artillery bait" drawback.
- Civilization VI: The Giant Death Robot is a mechanically unique super-unit in that, rather than be upgraded through unit promotions, its powers — like jumping over mountains — come from unlocking Future Era technologies on the Tech Tree. According to the Civilopedia the humanoid form makes the GDR easier to pilot through Motion Capture.
- The Legend of Korra: Kuvira's colossal Magitek mecha suit and its Wave-Motion Gun are powered by spirit vines, letting it drain limitless energy from the Spirit World and No-Sell the EMPs that disable conventional mechas.
- In most versions of the Transformers franchise, the titular Transforming Mecha need to consume a type of Pure Energy called Energon to keep going.