At first, Dragon Ball Z: Harukanaru Densetsu can be a bit confusing. The tutorial is lengthy, convoluted, and yet vague at the same time, always referring you to other categories instead of answering what you want to know directly. After a little trial and error it begins to makes sense.
Unfortunately, that's when the reality sets in: this game isn’t going to offer much strategy. The play flows like this: you move around on limited pathways on a map and encounter random battles like in any RPG, and then you fight a boss at the end. Battles are of course fought with cards. Yet unlike many card games where you summon different creatures, affect areas of the field, and manage various counters, DBZ: HD uses a simple numbers system. Each card has a power rating and a guard rating. If your power rating is higher than your opponent's, then the special ability on your card is activated (which could be an attack, an item, running away, etc.). If your opponent has a higher power, and has used an attack ability, then your guard rating determines how much of his attack you will "block."
For the most part, that's it. Much later on, the game introduces combo cards, but it's too little, too late. Choosing cards comes down to whether you play your strong card now, or use a weak card instead in hopes that something better will come along. You can attempt to strategically play your cards, but the major deciding factor is luck. You can beat entire missions by randomly choosing cards and not even looking at them. You can plan out an elaborate succession of cards, and then the game won’t give you a card to attack with, and you’ll sit there throwing away cards until arbitrary chance allows you to go on the offensive.
What's worse, the game lulls you into a sense of security and then punishes you. The random enemies are all incredibly easy to beat, but then the boss character is always much more powerful. You'll think "Great, now I can use some real strategy to beat this guy." And it is kind of fun using cards to buff your defenses and then combine cards for powerful attacks. But it's entirely possible for the random shuffle of the deck to not hand you any attack cards for long enough that the boss will pound on you until you're too far behind to catch up even when an attack card shows up. So you lose and feel cheated because it wasn't even in your hands.
And then the whammy: you have to start the whole mission over. That's right - there's no mid-mission save system. And one mission can take a long time, maybe 20-30 minutes. Which when repeated, is another tedious slog through easy random encounters and then a boss that might just not let you attack again. Ugh.