As for the whole crossover thing, I would like to see a Golden Sun fighting game with the mechanics of either Smash or Pokkén.
Yup, same here, and I'm not sure why more people aren't keen on the idea. The only reasons I can think of are that they think there would be too many clones and that Nintendo would just never make such a game. The latter is definitely true right now, but as far as clones go, there is significant latitude in how the same Golden Sun move could be implemented in a Smash-like game. If the roster comprised only GS characters, there's no reason why liberties couldn't be taken, as long as things didn't get too far-fetched.
Example 1: Odyssey. It differs between The Lost Age and Dark Dawn. Felix and Matthew could therefore have game-corresponding versions of the move. Isaac's could be a variant of Felix's. The move could also take on a different role for each character, dependent on fighting style. That is, the optimal circumstances for Isaac to use the move would differ from those for Felix, and his would differ from those for Matthew.
Example 2: Gaia. Does it act like it does in GS, or does the ground open up in one spot, then another, then another, progressing from in front of a character to in back of them? If the former, is it targeted in front of the character or surrounding him? If the latter, does it make a wave in so doing, or does the attack keep happening at each hitbox until the sequence finishes?
Frankly, I enjoy talking about a Golden Sun Smash-like game because it's exciting to think about all the ways it could be done, regardless of the probability of such a game ever officially happening. I know that there had been such a game in development by someone at a GS fan site -- it was sprite-based, and titled "Golden Sun Battle Revolution". Might have been at Golden Sun Realm, in which case record of it is lost, thanks to the forums going away, and I can't find anything about it via a search.
But think about it. The roster would have all 16 adepts from the player's party throughout all three games, plus at least the six main antagonists that we actually fight against. Characters such as Moapa, Briggs, and the Colosso warriors could also join the fray. Maybe Alex, too, should an appropriately awesome and believable moveset be able to be made for him. Even when you consider very similar characters, there's enough diversity -- as explained in my example paragraphs -- in the possible implementations of their moves that cloning could be outright avoided in most circumstances. In fact, the only instance I can think of of two characters who couldn't help but be semi-clones at best is Menardi and Karst, since their move pools aren't as big as that of any protagonist's, and they share some moves.
There's plenty of diversity in Dark Dawn's cast, alone. Himi is completely unlike the other three Venus adepts, as is Sveta compared to the Jupiters. And two characters -- Karis and Amiti -- can use bows, perhaps influencing the optimal range for the rest of their movesets.
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