The reason I changed Diesel is the main antagonist is because he appeared WAY more than Diesel 10, who only appeared in specials and one episode. Diesel is easily identified for antagonising steam engines and his behavior make him fall as the most antagonistic character
Whoever keeps switching them around needs to stop.
IDK about My Little Pony, but I think what the two Diesels have is fine. You'd have to take that to the admins but if you want to change their summaries to one of the main villains alongside said Diesel, I don't have a problem with that, but in future, take something like that to admins of this wiki.