Mister Element was originally a scientist Al Desmond, a scientist with criminal leanings who devised an elemental gun which had varying effects depending on his element of choice. Taking Central City of Earth-One by storm with his criminal gang (themselves modeled after four elements), he promptly faced the town's new hero the Flash. Despite thinking quickly on his feet and having tremendous adaptability, Mister Element proved no match for his fleet footed foe.
Mister Alpha was a mysterious man who sought to fulfill the prophecy penned ten years prior, when eight prominent students were gathered into a professor's office to write down what accomplishments they predicted they would make a decade into the future. Hence, Alpha began using the various sciences to his ill-begotten advantage, such as chemistry to break into a safe, geology to plunder a mansion and best the Atom and Hawkman, meteorology to calculate the sole casino unaffected by a hurricane while coating himself with phosphorous to render himself immune from Doctor Mid-Nite and Black Canary's attack, and mastery of zoology to sen rare birds as a distraction while using electricity to render Flash and Wonder Woman near-death.
After his initial defeat he returns with a new scheme, and a gadget to facilitate it. The Philosopher's Stone allowed Desmond to transmute elements instantly and far more efficiently than his own device, hence he changed his alias to Doctor Alchemy. After an initial rematch with the Flash, he joined fellow villains on Earths One and Two to form the Crime Champions, battling the Justice League and Justice Society before reforming. However, Professor Zoom... the Reverse Flash, tried to turn Desmond back towards evil doing. Thankfully his fiancee turned wife Rita helped him stay reformed, even when his own "cosmic twin" (rather, an energy duplicate of himself) Alvin Desmond took over the Alchemy alias for good.
Meanwhile, or rather decades prior, Mister Alpha's own scheme was crashing down around him. Faced with the assembled Justice Society of America, who had all been saved and/or revived by his former classmate Paul Turnbull, it was revealed that Alpha was in actuality Ted Kincaid. An investment banker who lost his fortunes in the stock market, he sought to use science to steal big and frame another. It should be noted that in America vs the Justice Society, the Flash mentioned that Kincaid reformed after his criminal misdeeds.