Shanghai Robotics Company:
Base of operations: China
Aesthetics: Sleek, smooth, red, green, and gold color color scheme for a patriotic look.
A government owned company, Shanghai Robotics Company (SRC for short), was founded in response to the alien attacks. Not wanting to fall behind the west (or worse, Japan), in the giant robot industry, the government spent millions to create a giant Mecha as quickly as possible. Their main concern is looks however, as the government wants the prestige and propaganda potential from having a giant robot first, with the defensive uses of the mechas being a secondary priority, with then planning on making better models after their first's debut. They will definitely succeed in making their own giant robot, how said robot will fair in battle is another question entirely.
Her Royal Majesty's Mecha Corporation:
Base of Operations: United Kingdom
Aesthetics: Emulates the look of royalty and chivalric knights in honor of Queen Elizabeth II, who's still alive in 2050.
Founded as a subsidiary of the Royal Robotics Corporations, the rapid investment from stock investors and the government made the subsidiary quickly take over its parent company. They now focus on giving the UK its own giant robots to defend the UK, while also honoring its royalist traditions.
Nikola Tech.
Base of Operations: United States of America
Aesthetics: Small, smooth, white and green, environmentally friendly look while also futuristic and moder.
Founded by an entrepreneur famous for his innovations in electric cars and renewable energies, Nikola intends to make a Mecha that is 100% environmentally friendly. Using only recycled materials and running on green power, Nikola's robots promise to protect the planet, from monsters AND pollution. (even though critics say such a robot would have many flaws even if they manage to somehow make one)
Emirates Electronics
Base of Operations: United Arab Emirates
Aesthetics: Dark, stylish, modernistic, lots of advertising
Emirates Electronics was originally a tech firm made to expand the UAE's tech industry, but with the rise of alien invaders and increasing trend towards giant Mecha girls, EE was repurposed for giant Mecha girl creation. Many investors in the UAE and the foreign market have invested into the company and its first Mecha giantesses. Although many critics point out that these robots could just be yet another vanity project that Dubai is famous for, and that the 7 promised giantesses (one for each emirate) will only be used to serve the egos of the wealthy class of Dubai
Organization of World Domination
Base of Operations: Somewhere in the Pacific Ocean
Aesthetics: Think if Dr Evil and Skeletor got together and designed this thing
An evil secret society of villains from all across the world who have come together and formed the OWD for world domination. By stealing and combining the technology and innovations of other robot companies around the world, they've gained the ability to build their own Mecha giantess(es) to serve their own evil schemes for world domination.