Thanos.. Maelstrom and Seid...
Even though Thanos blasted Maelstrom to no effect.. First, we don't know how powerful the blast was the Thanos hit him with and second, he never showed the ability to do a thing to Thanos in return. So, even if you believe Thanos couldn't do a thing to him, he never proved he could do a thing to thanos and thus it's a stalemate.
Originally posted by Galan007
Though I do not believe Maelstrom could necessarily beat Thanos, I do not believe Thanos could beat Maelstrom, either.They stalemate.
This. It was even implied in a later issue of Quasar. Basically he was traveling the various alternate universes trying to find the Living Laser who had jumped into the Watcher's viewing portal.
He stumbles upon a universe where he died and was unable to stop Maelstrom. Maelstrom and Thanos with the IG were in a stalemate "tug of war" with the Sun. The Sun is destroyed and they are still in their stalemate, not budging the other.
Back in 616 reality : The fact that Thanos had the full IG when he blasted Maelstrom and the way Maelstrom basically IGNORED the blast then was able to evade Thanos' heightened senses tells me that 'alt reality' fight wasn't too far from what would have happened if they did indeed fight in 616 reality.