I found out one useful thing: The special bonus of 50.000 points.
You get this when you finish a round with the timer showing the same digit twice, like 77, 66 or 55. You can get this in each round, so you cab take cool 100.000 points per enemy from this.
It can be quite frustrating to time this but by saving and loading you have infinite tries.
Playing on Level 1 the enemies block practically everything but stay passive mostly.
When you set the difficutly to Level 4, like it is in Highscore and Caravan, the opponents will be a lot more aggressive but they block a lot less and you can get hits a TON easier with something like Chichi-Nene's "-> B" attack.