Incineroar was met with much praise for its Heelturn Wrestler basis, plus the Z Move it has was considerably a favorite.
On the leaks, however, as some pointed out, the leak says it's 27 minutes long. I'd like to mention this about leaks however. This one seems to be heavily based on piggybacking. Also, Pokemon Let's Go! has been confirmed to only have one new Pokemon outside of Gen 1 only and Gillyball and Gildragon sound VERY FUCKING STUPID for a Ghost/Fire type. Other than that this is already fake as fuck, plus, Isaac I don't see getting in Golden Sun because the franchise is VERY NICHE because of how many sales it didn't get in its two game entry run. The company that made it now makes Mario Sports titles. Many people would say "But relevancy and popularity didn't keep K. Rool out!" It sure as hell kept Chrom, Lyn and Waluigi out, at least from the last game in Chrom's case. Hell, you could say the same if Hector, Veronica, Celica, and Ephraim, the winners of Choose Your Legends for Fire Emblem Heroes, don't get in. I don't see Isaac standing a chance for that alone.