A little uncharacteristic of me I guess, but I thought it'd be fun to do this for once, since both finalists are people who I immensely respect, both in and out of this game. These are my predictions for this series:
BW: Though it can be argued that SoulWind's (yes, I'm capitalizing the W) team choice in semifinals wasn't the wisest, as seen by the glaring weakness to tier staple Ferrothorn, he still managed to play one of the most breathtaking games of the whole tournament, taking ABR down in match that ultimately came down to two Gliscor and two Gastrodon chipping away at each other. On the other hand, McMeghan somehow keeps pulling wins out of his ass with the boys™, as he affectionately calls the 2012 rain throwback he's used against his last two opponents. Funnily enough, I feel that Scizor is a pretty solid call in the current BW metagame, and even though that is a story for another day, it correlates with my thoughts for this game, as sometimes I feel that in his teambuilder insanity and late "prep", McMeghan ends up stumbling upon some gems that not even the most seasoned veterans would be willing to whip out on the big stage. With that in mind, I feel like in spite of SoulWind's status as the undisputed GOAT of Black & White, there is a very high chance this ends up being the game that decides the whole tournament, and I believe that its outcome will depend heavily on what McMeghan finds himself picking. Playing wise, it is hard not to favor SW, and considering that there is also a chance of Ro handicapping himself with some bogus technology, I would say that SoulWind should take this most of the time, assuming he doesn't get caught off guard by Ditto or Xatu or worse: TyraniBOAH.
DPP: Heavily SoulWind favored, in my opinion. Trained by PokeSpain's fiercest behemoths, I can't help but feel like this man's prowess in this generation tends to fly under the radar most of the time, as seen both by his results in DPP when it was in Smogon Tour and his incredible tiebreaker games in SPL, and I would even risk saying that it is SW's second best generation, even if he's had more success in RBY throughout this tournament. Plus, and this is probably what makes him as scary as he is, SoulWind strikes me as somebody who knows what works and what doesn't on a very profound level, and he isn't a person who would miss out on a chance to Iron Head things till they faint in classic DPP fashion, or even use some nasty NidoClef stall build and run away with the game that way. Lead Gyarados aside, McMeghan doesn't really seem to me as if he has found his mojo in this realm. Last time Forretress and Celebi were good Pokemon, obi (do not mistake with the Snake Draft manager and jerk connoisseur) and Kevin Garrett were the best stall players (joking, I'm not knowledgeable enough about Pokemon history statements like this one, but you get the idea). It's not like being a cheesehead to a fault in this tier is a bad thing in itself, as showcased by players such as Void, but when it starts bordering on ridiculous extents, it just doesn't pan out very well.
ADV: Slightly McMeghan favored, assuming his Salamence can do more than 30% to a Celebi at +1. A motivated McMeghan is easily one of the best players of all time, and this translates onto what he can do in the teambuilder. Considering how much he likes the tier at the moment, as seen by his result in ADV cup, and even after the disaster that was his game last round, I'm a believer that he will bring a polished team that he is comfortable with and proceed to showcase his prowess in this generation. A very sinister thing about McMeghan in tiers that he has taken a liking to is that a lot of times he doesn't end up abiding by the metagame's rules (as silly as that sounds), and a lot of his preferred teams showcase this, such as Vaporeon + Steelix and that Porygon2 + Calm Mind spam squad that looks like it could be a 2010 Golden Sun team. With that said though, SW is no slouch in ADV either, and he can definitely give his opponent a run for his money, but my gut says that his more standard and humble approach is prone to getting dissected by Smogon's most successful crackhead in his comfort zone.
God Silver Crystal: Big edge to McMeghan in my opinion. In spite of having a bunch of hiccups that ultimately ended up costing him his GSC match last round, he still managed to bless us with one of the best games of the whole tournament, going toe to toe with the most successful GSC player in recent times and almost pulling it back after some misplayed sequences in the Cloyster Spikes war (plus, lets not forget just how powerful the early game showing was as well). While it is unfair to criticize SW's GSC prowess, considering how limited his opportunities to show it have been, I can't help but feel like both his team choices and his playing can be a little uninspired in high stake GSC matches. Unfortunately, I don't find my gen 2 knowledge to be good enough for me to say anything insightful, but in my eyes this should be a Ro win as long as he stays away from the Nascar Cow.
RBY: Even though RBY play tends to be the most formulatic out of any generation, and luck usually finds a way to decide the winner, McMeghan did end up slipping a little in his game vs. Lavos in my opinion, as he failed to properly manage PP on his Ice-type moves and provided way too many opportunities for his opponent to wake up his sleeping Chansey (which, by the way, slept for like 11 turns between both times it was hit by Sing on the first try). On the other hand, SoulWind's Peasounay-inspired approach to RBY has provided him with unparalleled consistency in this tier, to the point where he was comfortable enough to take his series against ABR to a game 5 in it, something that only madmen could ever dream of. With that in mind, predicting a winner in RBY when the gap in skill is so small is a daunting task, but I do believe that SoulWind should be favored to take this one a vast majority of the time on (mostly) even luck. I don't think I've ever seen that man misplay in a high stakes gen 1 game, and that goes a longer way than most people who aren't as familiar with RBY would believe.
However, a glaring issue with this RBY game is that both of these man have been contaminated by the "Lapras is good in contemporary RBY" virus that the Frenchman of RBY has artificially engineered in laboratory. If any of these two uses that Pokemon, I hope that they get lucked as hard as humanly possible. If both of them bring it, I hope that the game ends in a tie and they have to go through the torture that is being forced to play a 2nd RBY game in a Bo5 of Smogon Classic finals.
tl;dr SoulWind's favored (IMO) in RBY, DPP and BW, while McMeghan should take ADV and GSC. DPP and RBY could go either way (insert variance madhouse and luck memes here), while BW is pretty reliant on the team choices the players end up making. Would be swell to see this man finally earn the trophy he's been grinding hard for so long for, but McMeghan is a sweetheart and I could never possibly root against him. All in all, I hope that this ends up being a set for the history books where both players feel satisfied with their showing, even if the trophy can only go to one of them