The Giants set was the last of the cheaper, pack-based team sets Epoch issued this year. For 250 yen, each pack has four cards. As with the other team sets of this nature, there are several parallel and variation sets to flesh out the release.
There is a four-star variation; 8 players have that variation. I don't know what the variation is here.
Note that as with other sets, players with a level-4 variation has level 1, 2, and 3 variations. Level 3 variation players also have level 1 and 2. And level 2 variation players also have a level 1 variation. Furthermore, the actual variation for any given player at any given tier may not follow the above formulas. I don't have time, money, or interest in verifying all of this data!
Furthermore, 12 cards have a "shockwave" parallel which I haven't seen.
Various levels of point cards could be found in packs; a total of 100 points could be exchanged for one of 12 autographed cards.