Grandmaster based on feats, since Glimmer has no combat feats
But to give some perspective on the Glimmer, he...
- Was one of the heroes at Wonder World, and as such is one of the greatest heroes in the history of the universe
- Ran perpendicular to time
- "I am power"...he was the power source that temporarily evolved humans to some superhuman level (capable of flight and survival in space, at the very least)