Mecha are so popular in the world of anime they have their own subgenre. These giant humanoid robots can be piloted as if they were fighter jets. At their most basic, they attack opponents with guns, missiles, swords, and more, all while offering protection from enemy barrages. But some of the best giant robots in anime can do a lot more than that. In fact, some of them can travel through time, use telekinetic powers, exude radiation, and even warp reality itself.
What are the best mecha in anime? Gundams - the space-faring machines that practically define the genre - are among the best of the best. There's also Eva Unit 01, which is powered by human souls and can tear Angels apart. Then there's the Super Tengen Toppa Gurren Lagann, which runs on pure spiral power and is literally a god. With so many incredible mecha, it's hard to avoid fantasizing about piloting them yourself.
Gundams are so integral to the concept of mecha that the terms are used almost interchangeably. They appear throughout the Gundam franchise, in everything from Mobile Suit Gundam and Gundam Wing to Iron Blooded Orphans. They are war machines that can be piloted in outer space, serving both to protect their pilots from harm and to take on intergalactic enemies. Appearances vary from model to model, but most hold some kind of weapon - often a gun or a sword - have wings, and even a recognizable masked face. Some models have the ability to transform, increase in size, or communicate telepathically.
When people say "get in the robot, Shinji!" they mean an Eva Unit. Eva Units are powered not just by their pilots, but also occasionally by human souls. Eva Unit 1, which is piloted by Shinji Ikari, is also running on the soul of Shinji's late mother. Eva Unit 01 is the most powerful of all of the Eva, though it's unclear if the whole soul thing fully explains that. Rather than shooting opponents or engaging in a swordfight, the Eva Unit uses unconventional weapons, like gigantic Bowie knives (and occasionally its teeth). Designed to fight Angels, the Eva Unit can use the body parts of fallen Angels to regenerate its own. It can also wild out in a "berserker mode" that makes it almost unbeatable in battle. That's a whole lot of power for a 14-year-old kid like Shinji to handle.
The literal translation of Super Tengen Toppa Gurren Lagann is "Super Heaven-Piercing Gurren Lagann," which should give you some idea of what kind of power it's wielding. It appears in the second Gurren Lagann movie at the end of a devastating battle with the Anti-Spirals. It was created when Lordgenome sacrificed his life to create a huge amount of spiral power, which Simon then absorbed into the Tengen Toppa Gurren Lagann - thus creating its super version. In this form, it is an omnipotent mecha capable of warping reality. There is nothing more powerful in the world of Gurren Lagann, and it is arguably one of the most powerful mecha in all of anime.
Knightmare Frames were created by the Britannian army and were intended to fight alongside tanks. Originally not particularly impressive, they became far more powerful once they started running on Sakuradite, a rare mineral found in Japan that's part of the reason for Britannia's colonization efforts. Each successive generation of Knightmare Frame adds new features - for example, the fifth generation is designed to be able to destroy other Knightmare Frames, while the eighth allows for underwater and high-altitude travel. Though primarily used by the Britannian Army, guerilla fighters like The Black Knights use their own Knightmare Frames in battle - which may explain the fifth generation development.