Laguna card was actually very easy for me to acquire. Believe it or not, I actually like those crazy rules. Same, Plus, Same Wall, Elemental. Yes, even Random. Sounds weird but I take just a teeny bit of offense to you saying that Same and Plus are dumb rules (Yes, I realise I am the dumb one for thinking this but I can't help it) http://www.ttadvance.com has made me realise just how strategic Triple Triad really is and how much more fun it becomes when you play anything but Open.

Anyway, Laguna can also be acquired from the CC Group on the Ragnarok in disc 4. That is providing that you were able to beat them all in Balamb Garden before. In fact, any missing card can be found in their possession. However, the rules they play with are quite random and it really doesn't get any easier than the Space rules. And remember that only a freak like me would actually LIKE playing all those rules

With practice (or by playing TTAdvance), you can get used to seeing the traps that the computer uses against you with Same and Plus.

Tip: Whenever playing a game with rules like Same, Plus, Same Wall etc., just remember that the idea that "bigger number beats smaller number" will ALWAYS take a back seat. Instead, look out for the tricks the AI is trying.
Tip˛: It's much more refreshing and fun if YOU actually start using the rules to your advantage against the computer. Always watch the areas where two cards meet diagonally (thus creating a chance for you to use the rules) instead of simply looking to take one card at a time by placing a bigger card.
Tipł: This is important. CHARACTER CARDS DON'T MEAN CRAP (Well, they do in Open only games) It's much better to use cards with close or similar numbers. Kiros, Edea, Rinoa, Phoenix and Doomtrain is my usual hand. Kiros is a nice all-rounded card and Plus rule allows it to be devastating. Edea and Doomtrain are good to use in corners but watch out for Same Wall. If you use one in the corner to start, then you can save the other one to use Same Wall, Same or Plus at a later time in the game. Phoenix serves a similar purpose as Kiros. Rinoa's just there because she has 2 A's.