Who can Black Manta beat with tech?

Sometimes Black Manta is portrayed as ruthless and fairly powerful (Aquaman's #2 enemy, and we know how powerful Aquaman can be). But his domain of operation is limited. Who is the toughest hero or villain could Black Manta beat using technology and a year of prep?

The Tinkerer? Mysterio? Hobgoblin? Doctor Octopus? Tony Stark? Lex Luthor (ha)? Dr. Doom (ha, ha)? Others?

Also, please indicate the winner for both:
1) underwater
2) out of water.

Bob agent of Hydra... manta will hack his blog, write some crappy stuff.. then pretend to be a hot asian girl and chat him up in instant messanger for about a week, ask to meet up by the coast.. then shoot him.

Underwater and with a year of prep? Heck, Manta could take everyone on your list, provided they don't have prep as well. Doom would be the toughest, but I think he could pull out at least one win against him. Now, out of water, his numbers go down dramatically. His tech is a lot less useful there, although he could still probably take out everyone up to Luthor or Stark with a year prep. No prep and he stops at Stark at best.