Probably for as long as there have been toys, there have been people seeking to make the same toy that someone else created, only a bit cheaper. Today, we tend to call such toys "knock offs." Knock offs are usually of inferior quality, and are, at best, of questionable legality. Yet they somehow manage to be rather ubiquitous. This poses a problem for the serious collector, to whom the legitimacy of an item is important, and to whom counterfeits pose a threat to the value of the originals.
So, yes, I own a knock off version of Raiden. Whatever that says about how serious a collector I am is up for debate. For the most part, I'll talk about the original toys, but there should be no confusion here: I do not own the originals, only this counterfeit version, for which I paid far too much in the early 2000s, only to find the same items available just a few months later for five-to-ten dollars for the whole set. If you consider that poetic justice, so be it.
Raiden is the name given to the combined form of the six "Trainbots." Although the molds, themselves, predate being a part of the Transformers line (being roughly contemporary with the Devastator molds of 1984), they are most known for their release in Japan as a part of the Headmasters toyline in 1987. From left to right, these are Shouki, Seizan, Getsuei, Yukikaze, Suiken, and Kaen (because these toys never came out in America as Transformers, they retain their Japanese-language names, rather than any westernized counterpart such as I would usually use, even when discussing Japanese toys).
Fans speculate as to why the Trainbots were never released in America. Most likely, it boils down to the reality that trains are not as popular in modern usage in America as they are in Japan. Although I'm a fan of modern rail, myself (I use Amtrak whenever I can, and advocate for developing high-speed rail as an alternative to flying or driving), the fact remains that trains just aren't as common here as they are elsewhere.
Despite being one of the earliest examples of combiner technology in the real world, Raiden is arguably one of the best-proportioned and stable combiners to ever come out of the Transformers line. While he lacks the articulation of modern Combiner Wars figures, he can point his weapon and keep it in the air far better than the original Devastator, and his shoulders don't have long visible pegs separating the arms from the torso, as with the "Scramble City" combiners. To be fair, a lot of this is accomplished with the help of parts that aren't parts of the constituent robots themselves (what is often called "combiner kibble"), but even most of this kibble is hidden in the back of the figure. If you're able to find a version of Raiden out there, I really do recommend it. It's a pity that it has never been made properly available in the US as a part of the Transformers line.