My explanations to questions that will certainly be asked or I have already received:
Q. Why is Sonic 2nd?
A. I'll just quote Abadango: "Sonic has high damage output and a good neutral. Can kill with up-throw. Has invincibility on up-b, good recovery, strong smashes, can kill early, and can play campy with side-b."
Sonic has great tournament results, and has rep from players such as Komorikiri, Octo, and Yoshi. No other character except for Sheik has the same amount of usage and results hence the placement as 2nd.
Q. Why is Mario so high?
A. Mario is considered the slept-on god of the game. He has no rep whatsoever but has, again in the words of Abadango, "Safe recovery with an up-b that has invincibility, hard-to-breach aerial hitboxes, good aerial mobility, good smashes and throw options, and large combo damage output." I don't think that Ally has anything to do with this, and that people actually think that Mario has untapped god-like potential.
Q. Why is Captain Falcon so high?
A. Deserving of this spot just from results. Saiya and Pichi have been placing 2nd~6th at several tournaments. Fast, good grab, combos, ability to kill early, b-air is a good tool. Hard to beat consistently just due to the amount of shenanigans that CF can do.
Q. Why is Wario so high?
A. Rep from Abadango, Nasubi. Good in the 2 stock format due to Wario Waft. Able to survive long due to heavy weight and good recovery.
Q. Why is Rosalina so low?
A. Though this was probably somewhat controversial in Japan as well, it basically comes down to Japan not having Dabuz. Luma can be killed fairly easily, and Rosalina's recovery is very vulnerable, some points which were probably points brought up during the discussion. Rosalina's somewhat disappointing results probably prevented her from entering A tier. Her best recent result was Top 12 by Kirihara, and Top 12 a little while back by Ice.
Q. Why is Olimar so high?
A. I don't personally agree, but here's SHI-G's explanation: "Has super strong smash attacks, strong ranged attacks, and combo damage potential, as well as various options when recovering and landing." The only Olimar main I can name is Shuton, but I don't particularly follow the character either. Abadango put Olimar as B- on his personal list, so this was likely controversial.
Q. Why is Meta Knight so high?
A. In my eyes this is completely justified, and he could have even replaced Olimar in A-. Salena took 4th at Umebura 16 with MK only, a feat that amazed everyone and made a lasting impression. He has an amazing dash attack, and Shuttle Loop is also very good. MK also has the u-air chain into Shuttle Loop insta-death combo. SHI-G's 9B, an MK main considers MK to be a potential A tier, which likely helped. Abadango put MK as B- in his personal tier list, saying that MK had potential to be A tier if the insta-death combo could be perfected. Abadango's opinion probably changed after he was eliminated by Salena's MK at Umebura 16 though.
Q. Why is Pikachu so low?
A. I completely agree with this placement for Japanese tier list. Japan doesn't have ESAM. The only two Pikachu players I can name off the top of my head are Lean and Shimitake, a SHI-G crew member. Pikachu hasn't made Top 16 in 4 Umebura tournaments, which is a really long time. It also seems like people consider Pikachu's difficulty to kill a big problem.
Q. Why is Lucario so high?
A. Rep from Gomamugicha. Solid overall I guess. I don't think many people had a strong opinion on him, so they probably said "meh, I guess he's around here."
Q. Why is Ness so low?
A. Kind of surprising seeing that Fsann, taranito, and Gakuto all have pretty good results with Ness. I'm not sure if this is completely representative of Japan's general opinion, but here's Abadango's explanation: "People say that he's very strong, but that's only his moves. His dash isn't that good, and his aerial movement is slow. He relies too much on the opponent making mistakes, so he can't be A tier."
Q. Why is [Character in D or E tier] so low?
A. No rep.