I have had good positions with the Hippopotamus opening with its Kings Indian structure(ranging up to +3 in evaluation) but in the end, the tactical superiority of the computer always gets in the way and I end up losing or drawing the game. The computer I am talking about is Computer Level 9 on Chess.com(Not to be confused with Komodo 8). My playing style is very tactical and aggressive, but I doubt that would work well against stronger Level 10. The openings that I am looking for are openings that are very positional in the beginning, but they also offer counterplay in the middlegame. Please suggest openings for white and black.
If you want to beat a 2200-2400 opponent then you need to be a 2200-2400 level player.
The hippopotamus type openings are doomed to failure according to one old GM. I find them very easy to beat but then I do not usually play 2400 rated people. OTOH they are not tactical type openings at all. Nor are they very aggressive.
If you want to play hardball tactics then play a more open type of opening.
You should master ONE basic opening and play that one. It is not the opening that wins, it is the player making the moves that wins or loses.
You should look at the French defense for black if you want to play that style. For white try a Reti. Or even just the Ruy.
A Sicilian would be better but is much harder to learn.
You're looking at this the wrong way. As you say yourself:
the tactical superiority of the computer always gets in the way and I end up losing or drawing the game.
Thus, it's really not a matter of opening choice: the computer is better tactically. The best hope you have of beating this computer is getting better tactically. Chess is a game of tactics, so ultimately tactics will serve you better in the long run.
That doesn't mean a good opening strategy won't help. The Sicilian has a reputation of being a better for black than other openings. Consequently, the queen's pawn is considered better by some for white because it stops the Sicilian.
But again, the best strategy is less about opening choice and more about learning to follow through with that opening to the middle-game, and the endgame by extension. And the best way to getting better at this is by getting better at tactics.
Even if you are good at tactics already, then try to get faster, and more accurate. This will ultimately help you in the long run.
tl;dr: My recommendation is Sicilian for black, Queen's pawn for white, and just simply drilling tactics.