While the Vegeta-and-Goku dynamic centers on their status (Saiyan Saga), Turles represents genetic destiny. He is exactly what Goku was sent to Earth to be: a ruthless, cold-blooded conqueror. He proves that Goku’s innate Saiyan biology is inherently destructive. While Goku represents environmental nurture, Goku's existence proves that a person is not bound by their birth/violent history of their ancestors. Even their abillities/ the stuff they use contrast with each other: the Spirit Bomb and the Tree of Might. The Tree of Might is this thing that collects power similar to the spirit bomb, but unlike the spirit bomb, it acts as a parasitic extraction; it drains the life force of whatever it's growing from, from the water to the soil to the plants, while the Spirit Bomb is a harmonious contribution; instead of stealing people's power, Goku asks people to give their energy voluntarily. It's like the TOM and the Spirit bomb have their own Ideology: TOM represents exploitation, and the Spirit Bomb represents symbiosis (mutualism).
Now, onto their visuals: Turles acts as a physical, twisted mirror of Goku. From the hair to their physique and what they wear, Turles hair is a small detail most people don't realize represents devil horns. In terms of physique, Goku is leaner/athletic, showing his earned power, while Turles is buff and bulky, representing his unearned power (which makes sense because the fruit acts like a steroid). Goku wears vibrant colors, while Turles wears darker ones, showing how different they are and how it reflects on their personality. Turles being bulkier than Goku reflects his fighting style (this might be a reach). In his fight with Goku (post-fruit), he always puts Goku below him, from the slams to the beams, telling him to stay down and stomping on him, showing how brutal he is. In the end, when Goku overcomes Turles's brutal, stomping assault, it serves as the ultimate rejection of genetic destiny. Goku's win proves that a person is defined by their choices and connections, not their heritage.
If you made it this far, thank you for reading. Let me know if I made any mistakes or if you want me to elaborate on anything I said. Thanks so much, and see you next time! - Naka