HI SCORE Mode means you don't get any continues, so you have to earn 200,000 points in one go. This is quite easy with the right character.
-Select Chi-Chi & Nene as your character, they are the twin girls third from the left.
-Begin the match. Unfortunately like some of the other ACA NEOGEO games your opponent is random so you can't select a pushover for an easier beginning. Whoever you fight, you are going to spam "Toward Your Opponent + B Button" into oblivion. This will make her do a double hit kick at your opponent, and eventually you'll corner them and just keep doing this until you win the round.
-Sometimes if you're close enough the girls will do do a throw that will cause your opponent extra damage. Between this and the kick spam hopefully you'll be able to reel off a few perfects because that'll give you a nice score bonus and speed things up. If not, don't worry because you can just brute force grind the 200K out.
-What I would do is win a round (hopefully getting a perfect), then almost winning round 2 then letting the CPU win (for extra points), then win round 3 (with hopefully a perfect again). I did this process until I reached the appropriate point threshold.
-An extra strategy is keep restarting until you get matched up with Susano, Gokuu, or Igret. They are much easier to get perfects on than the other characters.