Hi everyone! I'm new at smogon's forum, but I've played competitively since X  and Y came out. I did a lot of ORAS battles and I really want to help out at updating new UU viability rank. I hope you would take some of my thoughts to consideration. Here's a few od them:
 Dragalge: from  
B to B+. First of all it's typing is quite handy which gives it a lot of switch-in potencial fairly common typings such as grass, fighting and water. Second of all it's really endurable which makes him nice revenge killer. For example:
252 SpA Sceptile Dragon Pulse vs. 200 HP / 0 SpD Dragalge: 170-200 (52.9 - 62.3%) -- guaranteed 2HKO (added mega Sceptile's base sp.attack)
And probably the biggest shocker for me - it hits harder than a fckin Hydra:
252+ SpA Choice Specs Adaptability Dragalge Draco Meteor vs. 252 HP / 0 SpD Suicune: 340-400 (84.1 - 99%) -- guaranteed 2HKO after Leftovers recovery
252+ SpA Choice Specs Hydreigon Draco Meteor vs. 252 HP / 0 SpD Suicune: 301-355 (74.5 - 87.8%) -- guaranteed 2HKO after Leftovers recovery
I know, modest specs Hydreigon isn't a thing but that's just for comparison. As B rank description says it has more notable flaws than those above them like eq weakness, bad speed and no real way of hitting steel types. Overall I think it's a fair trade-off.
 Mega Swampert: from 
A- to B+. Okay I love this mega and it reminds me my new years resolution, but i don't think it matches A rank too well. It is indeed a good weather sweeper with really good attack and decent speed, but weather isn't too accessible in UU. Drizzle is BL and probably the best prankster weather support, Sableye, went to OU. It has literally one set which is sweeper set and no reliable recovery. Regular Swampert can hit harder with a choice band, set rocks as a lead, and have some form of recovery with a chesto - resto set. As I said before grass is a common typing, especially in UU (seroisly check out how many grass type moves users are there) and you need rocks on the field to beat for example sash Galvantula with energy ball. And onec again as B rank description says "They can all still function very well given the right team support". It perfectly matches with the things i said before. Still really stong pokemon, but it requires a lot of support. Speaking of.....
 Meowstic-Male: from 
Unranked to C. This is kinda Sableye's replacement, but it brings some new stuff too. It has a lot of supportive moves to go along with it's ability - prankster. To name few: t-wave, toxic, screnns, trick, yawn, trick room, sunny day and rain dance and 
heal bell, which makes him the first priority status healer in history. It's bulk is even better than Sableye's and it has usable sp. attack with access to calm mind. Unfortunately no will-o wisp and recover or taunt really hunts it a lot.
Altaria to D rank- well, it's technically still UU, right?
Once again I hope I helped out a bit. It took me like a 2 hours to write it and I'm a little bit nervous.
Also I'm from Poland and our flag is white and red. Some random generator chose Voltorb as my avatar and Voltorb is red and white. Conincidence? I think not :)