darkSpyro

So I have seen many people asking which S2 should I get and the same for Lightcore.If you have a question about which ones to get post here.This may be moved to Toys and Merchandise some time but while it is here lets get posting.

All of them

Based on Wow Pows, my recommendations are these. Anything with * is just based on what I hear rather than from experience.

*Wrecking Ball: This recommendation is more personal... But... DISCO BALL! According to the guide this raises the damage of the Force Field by around 30%, which I believe means it does damage in the vicinity of 80 now. Not a huge boost. I'm only recommending it based on lulz/epic factor of the Force Field becoming a Disco Ball because otherwise it's not that worthwhile unless you're a big fan of him.
Slam Bam: Sleigh Me! is a worthwhile upgrade. It makes the dash get replaced by an awesome sleigh which does ticks of 30 damage to anything in front of it. It also extends the length of the dash. With Slam Bam being the tank that he is, you can easily use this well, yet it finally fixes the escape issue that somewhat plagued him as well. It also, of course, gives you an oppurtunity to switch between his two great paths.
*Sonic Boom: I know I kept saying I hated this upgrade... Hear me out. The guide says Super Baby takes more hits and does 60 damage for one hit. Finally, a perfect companion for Siren Griffin to go with! Just because it will improve that path, go for her. I know it improves Medea even more, however, Siren is a very fun path, that was always bad at Battle, and by buying her Series 2 you can finally get to keep Siren up in the midst of player versus player without getting laughed at.
*Lightning Rod: The lightning might give him a quick alternative to the Grand Lightning that would help his mobility a lot. He would be able to use a good ranged move without being stationary(I'm sorry, but I think regular lightning bolts are just an awful move).
*Stump Smash: Exactly the same case as Sonic Boom. This will make Smash 'N Bash usable against other people and make Nut Crafter even better than it is.

*And LightCore... NONE OF THEM! They are worthless, cheap gimmicks. They lack Wow Pows and path switching. Not as bad a case with new Skylanders, but they are still more expensive.
Either way, all Giants have LightCore tech built in without forcing you to pay premium, so if you really want to see it in action, buying those and getting new characters instead should be more than enough to whet your appetite.
Honestly, I'd only feasibly say you should buy Jet-Vac and Shroomboom- and only if you can't afford the Starter Pack/Dragonfire Cannon(in which case you really shouldn't be investing in SKYLANDERS anyway).