I love how there can be so much variety in this game and how there's soo much of a learning curve. But I must ask what's probably a silly question. Do you game vets consider this game more of a power struggle or can one whoop up on some folks with a well balanced deck and good skills & mastery of the game rules?

Well, certainly, there have been symbols that were stronger than other towards the end of formats, but generally there is a lot of balance and you can win playing off any symbol. Most of the ridiculous stuff has been banned, save for maybe 3 cards in block 3. I would say that every symbol probably has a stable card, but the only card I can think of that should have had 4 copies in every deck was Olcadan's mentoring and it was appropriately banned.

There aren't that many staple cards. Given the game's varied deck types (that is, resource system, where typically characters focus on one of twelve resources, and then within each of these resources perhaps a few different variations are possible) there are cards that might be staple in some decks, but not in others. As the paranthetical above indicates, there are a few more deck types given that we have a few more 'colors' than that-other-game. As such you'll find that ALTHOUGH there may be quite a few 'must-haves' they are such-haves that there are several different mutually exclusive must haves.

Perhaps an example:

Ka Technique: Its got a great contrl scheme. If attacks are doing damage, your turn, or your opponents turn, you can blank an opponent's foundation, giving you a bit of a breather sometimes. HOWEVER, though the card has Earth, Death, and Void as Resources, it might not go in every such deck. For instance, some decks may wish to be a bit more aggresive than that, and want to focus EVERY card in their deck to damage. Other decks flat out don't want to take opponent's damage so they might not include it because they don't plan on taking damage from an opponents attack ever. Other decks plan on just killing in ONE HIT, so including a card like this (which assumes you're going for more than one attack to kill) might not be the best bet.

Interestingly though, most UFS players would call this card a 'staple' right now. I consider it such. However, it doesn't go in every deck type, not even when you restrict it to the decks that can play the card. Not sure if you could say the same for such 'blue'ish things and certain 'counter' things in a game that has 'spells'.

Also note, Ka Technique is an uncommon. There are some rares and ultra rares that are pretty tasty in a similar way, but again, they are restricted in their 'universal' application due to the restrictions and deck variaties mentioned above.

Back a number of rotations ago, there where a hand full of cards who could really carry the "staple" monicker, Trade Your Passion for Glory and Olcadan's Mentoring. Both of these cards had fantastic abilities, of which Olcadan's Mentoring got banned for, but most importantly both had the Infinity resource, so they could be run in ANY deck. The injury assets, Broken Leg/Arm/etc. also ran as staple cards for a little while.

But everyone else has hit the nail on the head. Specific symbols will have staple cards, and specific characters will as well, but because most characters are competitive, and there is a wide symbol spread, you can't say that there is any particular card that must be run in every deck. At the moment we don't even get cards that are 100% staple for any particular symbol. The closest you get to now is probably Path of the Master (another infinity resource card), but that's generally only true for character themed decks, or ones who are heavily focused on using a character's specific support.