my opinions from being good on pokemon-online:
Randorosu is ridiculously good - CB Sand Power EQs murders EVERYTHING, i've had it OHKO Roopushin, Burunkeru after SR and do 73% to Hippowdon. if your opponent loses their ground resistant pokemon and you switch this in (remarkably easy considering its resistances - this thing is fairly bulky too, can revenge kill Garchomps as it survives Outrage after SR along with Boiling Water when it's not in rain and ****) something is going to die.
Kobaruon isn't as powerful as Terakion but its bulk helps it easily set up SDs and Steel / Fighting is not bad coverage at all especially when accompanied by Stone Edge. that and people don't seem to know what to do against it. in this hard hitting metagame i like it more than Lucario
Doryuuzu is obviously insane, the balloon item gives it a ground immunity and so not even Ditto can revenge it unless the Doryuuzu runs Brick Break for some reason. very very hard to stop
Zoroark is a pest especially when it NPs but not that great, my team seems to shut it down pretty easily. DITTO!
Sazandora is a mixed bag. i ran Taunt / Draco Meteor / Surf / Fire Blast which at some points completely destroyed the opponent but at some points died without too much trouble... it's not the strongest / fastest pokemon around and dark / dragon offer pretty redundant coverage. i do enjoy its immunities though, especially water which it can abuse easily and i found myself missing its switchin chances when i switched it with Genosect.
Jaroda is far better than you think it would be. it does a good job at destroying unprepared teams with that ridiculous ability as well as Sub + Leech Seed. people don't seem to be using it to its full potential, though; if it's Scarf it needs to be kept until late game / until people are sure the pokemon who pretty much 100% counter it (Nattorei, Scizor, Heatran, Sazandora, Blissey, Ditto) are gone. some people are using it well though.
Ononokusu has been underwhelming but this might be because i run Ditto and just revenge it after it does whatever. not having a secondary STAB means this thing isn't overpowered like everyone seems to think it is.
i haven't seen many Hihidaruma but let me assure you nobody runs Daruma Mode, and for good reason as it is rubbish. regular Hihi does hit things hard though.
Aianto hits hard as hell and is really fun to use except sometimes it's not really fun to use, usually when i end up missing everything with Hustle
Shandera is less broken as everyone seems to be running Shed Shell on all their important walls but it does what it needs to (kill everything that's moderately slow and weak to anything). it doesn't kill Politoed very well though : (
speaking of Politoed yeah it is good. i never realised it could be so bulky, people have caught on and it lives for a surprisingly long time if you're not retarded and don't sacrifice it. imo Sand = Rain (sand maybe having a slight edge) > Sun > Hail. i have seen 0 hail teams so i am assuming it sucks.
Chiraachino with its Skill Link bullet seeds and other such nonsense was really annoying until i got Kobaruon to stop being murdered by Draco Meteor every time a dragon switched in and Kobaruon pretty much stopped this as well, and then everyone started running Steel types... yeah it's not that good.
speaking of Kobaruon i almost lost to a team of 5 Scarfers using Assist and a Dragon Tail Dragonite as everything just repeatedly switched me out. it was funny until it almost beat me. but i ended up with Kobaruon as my last pokemon and swept the guy. creative **** does work.
uh yeah. this metagame is great fun to play when you stop with the crapshoots and get a solid team! lots of stuff works (read: 90% of the 5th gen pokes) so just try everything. also, if you're any good at predicting in 4th gen and learn what pokemon use what relatively quickly, you'll decimate 95% of the players.