Super Deformed
Not based on any particular scale, the super-deformed style features comically-proportioned models, the most noticeable features of which are their very large heads. Super Deformed Gundam kits are often very easy to construct but offer very limited articulation and require paint and detailing to truly "finish" the kit. The most famous line is the BB Senshi (or "SD GUNDAM BB Warriors" in English). There are also separate product lines: for instance, Superior Defender Gundam Force and Ganso SD Gundam (discontinued in the 1990s). Most kits of this line are from the Musha Gundam series and the Knight Gundam series.
1:144 scale
The very first kits have been running for 30 years (starting with RX-78-2 Gundam) and are routinely re-released by Bandai. As these kits are limited in articulation and require glue (for the early kits) and paint to assemble, these have retroactively been categorized as NG (No Grade), to differentiate them from FG (First Grade).
During the mid- to late-1980s, the quality of molding improved and HG (High Grade) level kits were introduced in 1990, starting from the titular mobile suits of the first four TV series. These limited-run kits featured full snap fit assembly, an "internal frame" (for the first two kits, which provides better range of motion and were more poseable), and utilized the molding technique known as System Injection, wherein multiple colors would be cast on the same part.
In 2010, Real Grade (RG) surpassed HG as the top-end series of the 1:144 Gunpla line. The kits feature extensive detail and articulation, as well as a poseable skeletal frame comparable to the 1:100 Master Grade kits. The first RG kit was the 1/144 RX-78-2 Gundam, followed by the 1/144 MS-06S Char's Zaku II.
1:100 scale
Just like the 1:144 scale model kits, these kits started about the same time with the very first 1:144 model kits, again starting from RX-78-2 Gundam. "Generic" 1:100 kits may also be called "No-Grade" (NG 1:100) to differentiate from other specific 1:100 kits. Later kits (from Turn-A Gundam onwards) are clearly inspired from the post-HG 1:100 kits and features a similar (or greater) level of quality and detail.
Beginning with Victory Gundam in 1993, the HG line would shift to relatively well detailed larger scale kits in the 1:100 scale. There were need for little painting and detailing. These applied for the 1:100 scale models produced between 1993 and 1998, including Victory Gundam, G Gundam, Gundam Wing, Gundam X, and New Mobile Report: Gundam Wing Endless Waltz. Each TV series would receive on average between 6 to 8 models in this scale and grade.
Master Grade (MG) models were first introduced in the summer of 1995, designed and made to higher standards than most other models. These take much longer to construct and are often much more expensive than their lower-grade counterparts. These kits consists of features similar to those of the HG and HGUC but better. This line of plastic kits was the first to feature a movable inner frame system which enables extensive movement and bending of joints. The popularity of this line was so great that a lot of old and new kits from non-graded series were cast as Master Grade models. The vast majority of MG offerings are from Gundam, with the rest coming from mechas in Patlabor and Dunbine, as well as character figures of Dragonball Z, Kamen Rider W, and One Piece (under the name of MG Figurerise). As the MG line has become a symbol of Gunpla, Bandai released another lineup called Real Robot Revolution (R3), for the non-Gundam type real robots like Layzner and L-Gaim, made using their experience in MG model production.
1:60 scale
Bandai release 1:60 scales to the main mecha of major TV series. These are non grades or TV grades models, and the main line of 1:60 scale. Early 1:60 kits, like other scales, where simply a bigger version of the smaller scales. In the early to mid 90's, 3 High Grade EX models of V2 Gundam, Shining Gundam and God Gundam from the V Gundam series and G Gundam series where release, featuring more details and gimmicks than its smaller counter parts. Bandai also created a much more detailed series of figures. The Perfect Grade (also known as PG) model kits come in standard 1:60 scale but are superbly detailed in terms of color and its inner frame, as well as normally possessing more points of articulation, such as hands that articulate at the knuckles. Perfect Grade kits were mainly used for developing new plastic model technologies, a function currently taken over by the Master Grade series, and typically need a few years to develop each kit.
1:35 scale
Universal Century HardGraph does not primarily center around the humanoids of the Gundam universe. Rather, it centers on military things on a more conventional scale such as land vehicles, tanks and troops. However, some kits do include detailed to-scale mecha parts which are particularly useful for the creation of dioramas. For instance, the Anti-MS Squad kit includes an articulated lower Gundam arm.
Other/Mixed Scales
There are various other scales, like the Mega Grade's 1:48, the Speed Grade's 1:200. These scales are less dominant in the Gundam Model line.
A 1:400 scale model line is designed for large mobile armours and battle ships in the Gundam Collection line, which the line's ordinary mobile suits are figures, not models. Only extremely large units like Mobile Armours and Warships need assembly. These models are pre-coloured models, and the warships need minimal assemble. An earlier line of model, the High Grade Mechanics, with a scale of 1:550 held a similar function in introducing large mobile units, but the line only consist of 3 mobile units from 0083.
Another high-detail line is the EX model, in scales of 1:144 and 1:100 (non-humanoid units like aircraft) and 1:1600/1:1700 (spaceships), ranging from the Universal Century to Cosmic Era productions. This series is not Gundam-exclusive, having models from other series like some of the jet aircraft from Sentō Yōsei Yukikaze and at least one aircraft from Ace Combat 5.
Special Editions
Over the years, Bandai released special limited editions of various kits, usually as competition (such as the yearly Bandai Action Kits Asia (now Universal) Cup held in Hong Kong) prizes, or as an event-limited (such as Japanese toy expos, movie launch premieres) item, although sometimes these kits are sold as limited web-shop items or discreetly sold by Bandai. These kits usually come in clear plastic, metal-plated (certain kits are in so-called 24-k gold finish), "gloss-finish", "pearl-finish", "titanium-finish", or any combination of these. Their prices are usually much higher than their regular-release counterparts.
