According to the
Amazon Description of the Team Pack, I would say that the Gremlins Adventure world is definitely in (as will also be case for every other new IP).
What is S2 going to introduce that S1 doesn't have already?
E: Beaides new IP's of course...Also, are any S1 things impossible to get now? I've got a few things left to finish up.
Well, from what was already been announced, we know that they are introducing few modes and a few new character mechanics. Battle Arenas (a 1-4 Mode featuring a variety of competive events, with each Season 2 pack unlocking brand new Arenas and events. Each new Story pack is supposed to have a new Keystone mechanic (the physical portal puzzles). And from what we have seen of the characters, we have already seen abilities unique to these sets of characters, like, for example, Finn's grappling hook-like ablitiy & Sonic's rail grinding.
From what I have seen, All of Season 1 can still be found through online retailers. I haven't checked every retailer, but I believe that Toys-r-Us should still have everything (including their own exclusive, Jay from Ninjago). It might be harder if you are only buying locally, however. From what I have heard though, The Midway Arcade level pack is not easy to find in store, I'm guessing that they felt it would be less popular of something?
I'm not interested in the Ninjango and the Wizard of Oz sets or hub worlds. I'm not missing much skipping them right, and just using alternate characters or hire a hero right?
Well, you won't be able to get every Gold Brick as both Adventure Worlds have (at least 26) Gold Bricks each & you also won't be able to unlock the Red Bricks from those Adventure Worlds (Ninjago's Red Brick unlocks The Way of the Brick which significantly increases the speed of building LEGO bricks.)
The Wicked Witch, despite not having an ablitiy unique to her (with the exception of unlocking the Oz Adventre World, of course), is a very convenient character to use. Not only can she do everything Gandulf can do, she also has Flight, Sliver LEGO Blow-Up, and Mind Control (she's a main stay on my gateway when playing the game, I can say that much).