Let's find a place for The Great Beast and Malachite by looking through the Champions Villain Volume 1 and see what genetics villains are there...
Doctor Destroyer (pages 15-43, including agents, supers associated with him, and robots)
Works: He is more likely to use his genetics knowledge to fix the flaws in the powers of other supervillains, but with a twist. He would either make sure such improvements could be turned off in case of betrayal, or add something in (much like the neural bomb inside Thoughtcrime to make sure yet another mentalist will not betray him). He rarely creates clones, viruses, or mutations himself.
Kinematik (pages 71-79)
Works: Again, like Doctor Destroyer, he is not known for his genetics. He can't create mutants and such. He does know Eugenicist, the ancient ancestor of Genetics, which works as a better humanity via selective breeding. This, given time and a loyal group of followers, he can raise an army of more 'perfect' mutants within two generations or so.
King Cobra (pages 80-97)
Works: Primarily 'snake people'. King Corba's obsession with creating a horde of loyal serpent men is legendary. And making them out of humans, even more so.
Mechanon (pages 99-117)
Works: Another villain nobody would associate with geneticist. But he has used it in the past to create life ending organic destruction viruses which he threatens to unleash from time to time (and somehow has never released for one reason or another). His failer might be mostly because he despises organic lifeforms, it pains him to use an organic lifeforms to destroy one.
Doctor Phillippe Moreau (pages 122-125)
Works: "Manimals", uplifted animals with almost human body placement. Idolizes his grandfather. Surpassed his grandfather. Kinda works for VIPER, yet maintains his independence at the same time.
Joseph Otanga (pages 138-141)
Works: While the source is magic, he is skilled in changing humans into animals. Also, he is skilled in giving himself animal powers via the same magic.
Teleios (pages 221-225)
Works: Clones. He is well known for the love of himself, and this most of the clones he creates are similar to himself genetically (why work with inferior subjects, when everyone knows he is perfect).
While not in any book yet, I must say something about...
Doctor Lirby Koo
Works: Various branches of genetics. He probably was once forced to work for the Tiger Squad, so he is more than knowledgeable about superpowers and how to 'improve' them, suppress them, modify them, ect...
Now, to the subjects at hand.
The Great Beast
Works: Modified animals using some strange organic material he has discovered. The catch is that the substance can easily be given to the subject without causing pain, and results in superpowers without a loss of loyalty a pet would give to a master. And to The Great Beast, that is exactly what they are to him, his pets. He, in fact, prefers them to human company.
Works: Devolution Gun. Litterly, he has zapped people, plants, and animals back to there prehistoric counterparts using the gun. As part of the devolution, they are artificially conditioned to obey all commands he issues, if they understand it or not. He is working on a way to devolve birds into dinosaurs (he tried doing that once with reptilians, but only gotten dri gators).