Size class
Size class is how Hasbro determines the size and price of a toy. It also determines the amount of budget spent on the production of a toy, such as paint or electronics. The logic behind size classes is simple; retailers can order a case of toys, knowing exactly how much they will sell for and exactly how much shelf space they will occupy. All the Deluxes in a line have identically-sized packaging and cost the same price. When you run out of Deluxes, you order a new case and put them right back where they belong. This is incredibly convenient, especially compared to Generation 1, where the sizes and prices of figures varied widely.
Size class has not been consistent from line to line, with names often changed to affect marketability.
Beast Wars
Beast Wars had five size classes. The cheapest, with the price at US$5, was Basic. Deluxe was the next cheapest, being around US$10 in price. The two smallest classes are sold on cards to this day. The next step was Mega, with a price of US$15. Toys of this size were often shelfwarmers. Only six toys were sold as the next largest size, Ultra, with a price of US$20. The largest size, Super, was only attained by one toy, Optimal Optimus, which was sold for US$35. All of the classes larger than Deluxe were, and are, sold in boxes.
Beast Machines
Beast Machines continued Beast Wars' size classes, but increased the price of Basic to US$7 while lowering the price of Super to US$30. Supreme was introduced as a US$40 size class; Cheetor was the only Supreme in this line; a Supreme Optimus Primal toy was planned to be in this line, but was moved to Robots in Disguise. Two additional size classes, Deployers (US$5) and Beast Riders (US$10) would turn out to be short-lived. The size of Ultra toys were increased while maintaining the price.
Robots in Disguise
Robots in Disguise used the Beast Machines size classes, though the Basic price point was once again lowered to US$5. However, most of the toys at this price point were either Spychanger two-packs or redecoed Generation 1 small limbs, making them somewhat smaller and less intricate than previous lines' Basics (a notable exception is the recolor of Obsidian).
Armada
The Armada toyline replaced the Basic price-point with packs of three Mini-Cons, thus establishing it as the Mini-Con pricepoint, with a suggested retail price of US$6.50. It renamed or repurposed every other price point as well; the Deluxe pricepoint was renamed Super-Con, while the old US$15 Mega size class was effectively discontinued, taken up by role-play toys like Laserbeak.
The old "Ultra" size class became Max-Con, and a new size class priced at US $25, Giga-Con, was introduced. The US$40 class (formerly Supreme) was renamed Super-Base, and the US$50 class was introduced simply as "Unicron".
Universe
Universe used the Beast Wars size classes, but only had Deluxe and Ultra. After the Universe line as such had effectively ended, repackaged Energon toys were sold on Universe cards as discount chain exclusives, divided into the price points Basic (US$5) and Deluxe (US$8).
Energon
Energon took a somewhat random approach to size-class naming. The second pack-in catalog introduced the smallest size class as Energon (Basic), with the price being back to $7, and the other size classes as Combat (Deluxe), Mega Combat (the old Ultra price point, aka "Max-Con" during Armada), Commanders (the former "Giga-Con"), and Leaders (the former "Super Base"), with no size-class attributed to Unicron.
The third catalog explicitly referred to the price points as Energon Class, Combat Class, Mega Class, Command Class and Leaders Class, with no class listed for Omega Supreme. The fourth and final catalog continued using the terms originated by the third (although listed no price points for the combiners), but finally listed Omega Supreme as Supreme Class.
Cybertron
Cybertron changed the naming of some size classes, but retained others. Energon Class was changed to Scout Class, Combat Class became Deluxe Class, Mega Class was renamed Voyager Class, and the US$25 price point (formerly Command Class) was now named Ultra Class. The Leaders Class dropped the plural "s" and thus became Leader Class, while Supreme Class remained the same. A new Mini-Con Class was added for the Mini-Con two-packs, set at US$5. The Legends of Cybertron figures have a suggested retail price of US$3.
Classics
Classics keeps the Deluxe and Voyager classes, now called Classic Deluxe and Classic Voyager. Repaints of the Legends of Cybertron figures are released as Legends, with the MRSP raised to US$4, while a new Mini-Con class, now consisting of three-packs again, replaces the Scout Class price point at US$7.
Movie
Transformers, the toyline based on the 2007 live-action movie, retains the Legend (US$4), Scout (US$7), Deluxe (US$10), Voyager(US$20), and Leader (US$40) size classes of previous lines, while the Ultra and Supreme classes seem to have been dropped. Additionally, there's a new US$90 figure solicited as Ultimate Bumblebee.
