As for the gods, I think its difficult to rank the hardest pools in order. This will be based on how difficult I think it will be for them, in terms of a combination of match-ups and relative skill right now.
Most Difficult - PPMD's pool
Self explanatory. Lets not beat around the bush, PPMD arguably has the lowest floor of the gods right now. The only match-up I'm absolutely confident in him winning is against PewPewU and that's because he's truly the Marth Ditto master.
He's still PPMD though, don't count him out.
Second Most Difficult - Mango's Pool
Here's the thing. HTC was the worst Mango has and probably ever will play [adjusted for expected performance] - and I think losing to MacD and DruggedFox are both very unlikely. Especially DruggedFox now that he's switched to Falco.
Axe could prove troublesome, he's beaten Mango before. Mango is the favourite but wouldn't be surprised if Axe snuck in the victory.
Mango said his pool is pretty free and I have to agree. Don't count the others out though
Third Most Difficult - M2K's Pool
I actually think this pool outside of Nintendude is #free for him. Regardless of how he plays, he isn't losing the Sheik Ditto against Plup, or any Sheik for that matter.
He has a Falcon in his pool. And a Sheik's destroy Falcon's, especially one as explosive and aggressive as S2J. I actually think it'll be two quick 3-0's
Nintendude is the question mark. If he goes Marth, I think he'll win. If he goes Peach, maybe not.
Least Difficult - Hbox's pool
This new, improved and extremely consistent player isn't losing to Sheik and Icies at a major, no way. Perhaps at a local where things aren't as serious, but not here. Puff is extremely underrated. The only for sure losing match-up for Puff is Fox and he only has to face one in his pool and even then, I don't think the Fox/Puff match-up is nearly as bad for Puff as people make it out to be.
I didn't know where to put Armada.
Not only does he have to play two top Fox players, but two Fox players that are good at abusing the Peach match-up. Especially Silent Wolf. Lucky has also been getting much better at the Peach match-up.