If "plodder" refers to someone slow and uninspired:
* Dashing
* Energetic
* Dynamic
* Brilliant
* Visionary
* Trailblazer
If "plodder" refers to someone who works in a laborious and uninspired way:
* Innovator
* Creative
* Inspirational
* Efficient
* Resourceful
If "plodder" refers to someone who is methodical and painstaking:
* Impulsive
* Spontaneous
* Intuitive
* Unorthodox
* Free-spirited
Ultimately, the best antonym for "plodder" depends on the specific context in which you're using it.