All in all, it doesn't directly affect my research, but it is interesting to see the difference between what Sakurai says and what I've observed. When I started doing these tests, the reward pokemon appeared a lot more than that. After a while, though, it appeared a lot less to the point where I rareky see them at all (maybe my Wii's on to me

!). It just goes to show how programmers can program a game one way and yet in reality it [can] function in a total different way. Thanks for telling me about this, though! I don't really check the dojo anymore, so I wouldn't of caught this otherwise.
Well, I'd say Sakurai's 0.2%~ chance about the reward pokemon seems true for me.
I have played 10 hours of "vs Brawls" with all items enabled.
Played an additional 5 hours of "vs Brawls" with only Pokemon, Sandbags, Foods, and Barrels/PartyBalls/Boxes.
(Just background info on what I was doing, nothing really important)
(So, it was basically raining pokeballs. I set it up this was because I wanted the reward Pokemons to appear(I'm in the process of trying to get all music CDs). I also set it up so it was 3v1.
I played on the team that had 3 players. All CPUs except me. For a twist, I made it so that the handicap on my allies were at 80%. I left myself and the lone CPU on the other team at 0%. That was, I would have a higher chance of grabbing a CD(If it appeared) without interruption, since I lost about 3-4 CDs because computers kept attacking me while I was trying to grab a CD.)
(/End background Info)
I've played about 5-7ish hours of solo Brawls from Classic mode, All star mode, Events, Stadiums which had Pokeballs enabled.
So that's about 15-17 hours of Brawls with Pokeballs enabled, 5 of those 15-17 hours had only Pokeballs, Sandbags, Food, and Partyballs/Barrels/Crates/Boxes enabled.
I've only seen two out of three of the reward Pokemons. I haven't seen Mew yet. I've seen Jirachi once, Celebi twice(see below).
So, at least for me, I feel that the 0.2%~ chance that the Smash Dojo site has listed for the reward pokemon seem close to me.
BUT, there was a match where Celebi(trophy dropping Pokemon) appeared twice in a row. First, it appeared at nearly the end of the match, I didn't get any trophies because I didn't even noticed that Celebi appeared (I was trying out B-sticking/Wavebouncing for the first time so I wasn't paying attention to the current battle).
Then a notice came saying that I saw Celebi, this was when I realized that Celebi appeared.
Ok next match, Celebi appears AGAIN, and dropped the trophies.
My guess is because I didn't get any of the trophies Celebi dropped in the previous match, it appeared again in the next match so I could get at least one trophy. Either that, or I was lucky to see it twice in a row.