(Sent in by reader Brent, THANKS! I've just been burning off my common cards to train people all this time.)
On Supercard: I'm about 500 games in and have a few pointers.
So, the way the game works is like this: It's purely "who has the biggest numbers". As you play more games, you'll gain EXP, which slowly moves you up tiers and unlock more and more rare cards, unless you want to pay money for the chance of them early on. Not sure why you'd want to do that, because the game always has you up against people at around the same level, but there you go.
You can organize your cards by rank, and what you should do is put two pairs of male wrestlers who are at the top of your rank and who have complimentary symbols (the coloured arrows)- If you put two complimentary cards together, they get a bonus while tagging together. Then, you can increase your cards numbers in two ways: You train them by sacrificing cards, or you can combine them with identical cards to turn them into "pro" cards and that will give them a big stat boost. You can only combine once, and doing so sets the level cap for your card back to zero, so the ideal strategy is to level your card up all the way to the level cap, then to combine so you can do so again. This is the real trick to winning against your peers, as many people don't bother doing this. Also, it does not appear to have any effect if you combine two cards with levels as opposed to one leveled card and another non-leveled card.
While playing, pick your cards based on the attributes that will be judged. Use your stat boosting cards: You can only do it once per game, but there is no reason not to. The special abilities are activated randomly, and while you should take them into consideration, don't count on them. I suggest leveling up your diva first, as she will always compete alone and many people neglect them.
Eventually, you'll pick up cards of higher rank, which will totally outstrip your older cards, even if they are fully leveled up. (Well, not totally true: If you followed my advice your fully leveled card should be able to beat a card one rank up provided they don't have many levels) So, you replace them, make sure the men have a good tag team partner, and continue the process.
The real kicker in the game is the King of the Ring mode: Once you have a two full rosters (basically, once you have two diva cards, as the male wrestlers and support cards are plentiful) you can submit a roster to compete: These cards basically get locked down for a day or so, as the game spends a few hours getting a king of the ring bracket together, and then automatically battles each team round robin style, about one match per hour. Your cards have a stamina bar which does down every match and as it does so your cards stats will decrease. You can increase this by using energy cards which you get randomly for exhibition mode: Herein lies the hook, as in order to have your team do well enough to qualify for the actual king of the ring (and the fantastic rewards) you have to either log in every couple of hours, gain the energy cards randomly and use them to refresh your roster OR you can pay to have them refreshed once OR to have a bot automatically refresh your lowest card every match. Thankfully, it appears not too many people are doing those last two, and i'll find many watches that I won when both my and my opponents cards were completely exhausted of stamina, but you certainly can't count on that.
Final pointer:If this game scratches your OCD itch like it does mine, make sure to hold on to your cards that aren't part of your roster until you can combine them to make a pro card: The card catalogue that you build counts both regular and pro cards, so if you want to be a compleationist (for which there is no reward I've seen as of yet) you'll need to combine every wrestler card: Do so before you start burning them for levels!