I haven't played him yet, so I'm wondering too about which characters to team him up with. I'm thinking that his AV sucks at first, so maybe one should pack some Perplex and/or PC. I think Maelstrom needs a different kind of help than 5 Researchers. How about LE Diana Prince and two Researchers. Or Diana Prince and JJJ.
For other theme teams, you can pair him with Triton for the Inhumans Keyword for 297. Cosmic isn't viable because your only option in 300 is two Dominators and you might as well go with researchers for your enhancement because they are disposable and give you room for more. Monster isn't exactly great either. Either you run a Moloid and a 60 point figure (Kid Devil, Toxin) or you run some combination of Moloids, Man-Bat Assassin, Fire Demons, or Rock Troll. I guess you could run him with one Researcher plus 60 points.
I would prefer to run him with Inertia so that all characters within 6 of Inertia and 8 of Maelstrom have their movement halved then subtracted by two. A figure with 12 movement would charge for 1!
the researchers would be good, but i would honestly go with Triton from SI...i just played Maelstrom in Sealed the other day, and WOW. that dude really can hold his own. without something super deadly pulled like Quasar, no one could do anything, every person would damage Maelstrom to his Golden Clix and game over. i paired mine with Weapon X, but that was cause thats the only other awesome Clix pulled that day.
I had him paired with ice-cap in a sealed... you could throw the scorpio key on that team too to either give maelstrom crazy range, or to make Ice-cap an 8 range 12 attack psycic blaster with indom, which is pretty damn sexy :D