Just finished TCG 2, so here's a final somewhat involved update that I'm going to try to keep succinct. Therefore, bullet points!
Forgot to mention last time, but the special rule for the Fighting leader was that opponent Pokemon could not resist Fighting-type moves.
Taking down the Fighting Fortress opened up the Psychic Fortress and Colorless Altar. I go Psychic first, where for some reason you just have to defeat any 3 out of the 4 available peons to open up the leader, whose special rule is that Energy cards attached to KO'd Pokemon go back to your hand instead of the discard pile. Bad move when the Blastoise cards in my deck have the PKMN Power that lets you attach as many Water cards as you like on your turn.
The Colorless Altar is home to my new great nemesis, Seth - not the leader, just another underling. He wants 4 Double Colorless Energy cards in my deck before he'll duel me, and for the first time in the game, I don't have all that I need. Because I'm not insane, I look up which players in the game give you booster packs that can contain those cards and it thankfully doesn't take too long to get the needed stuff. His battle is super annoying in its own right, though, using what I guess is a TCG "stall" team. Lots of high-HP Pokemon with attacks that cause status effects, with as many Energy Removal cards as he can cram in to boot. I'm eventually forced to switch to my Fighting deck to break through, but even that has some problems until I'm able to get a Machamp on the board early that just runs him over. Screw this guy.
The Colorless leader didn't have a special rule for whatever reason; he just wanted 4 Meowth cards in my deck. Hilariously, one of those Meowths pretty much won me the duel because he got so unlucky with his card draws.
At this point, I've got all the Coins I need to enter GR Castle, where the final boss awaits flanked by two Executives. I discover I can't duel them without having the Legendary cards from the first game, though, so it's back to the first island to face off with the Grand Masters again. They honestly don't put up much of a fight.
Executive #1, Clay, has no gimmick - he just wants the 4 Legendary Cards in my deck. Not even really sure what his deck was built around because I kind of just steamrolled him.
Executive #2, Allison, had a deck built around Poison, which was annoying but certainly manageable at this point. She chose one of three special rules at random - increased Retreat costs, lowered Resistance for not-very-effective attacks, and one where cards sent to the discard pile are removed from the game completely instead.
The final boss, Villardi, didn't do any special rules or requirements at all. His gimmick was just that he would use one of 4 decks at random in a best-two-out-of-three format where the player could also switch decks between games. I won the first two games without issue, so, you know, kind of an underwhelming ending.
Villardi has so much fun dueling us that he realizes the true purity of the trading card game and promises to start playing it the right way instead of stealing people's cards. Yay, happy ending.
Finished up with an album of 308/441 - lots more cards in this one. Fun game - anyone who likes the original would enjoy this one too, I'm sure.