Um, you can use status moves as well

Rotom-H w/ Levitate @ Lum Berry used Will-O-Wisp
Rotom-W w/ Levitate @ Lum Berry used Thunder Wave

surprisingly that is still a failure, T-wave is absorbed by Seaking due to lightning rod. you are 95% of the way there lightning rod tripped you up. as shuckle-rock$ said status is legal.
Just so you know i could have been meaner and made only 1 pokemon work but chose not to use something with mold breaker and EQ
I'll give you guys more time and 1 hint only 8 Pokemon resist both ice and ground 6 of them have levitate 1 has wonder guard and the 8th resists both naturally.
Heat rotom wash rotom and bronzong were correct pokemon thunder wave was an incorrect move and charizard was an incorrect pokemon

I hate to answer my own but since no one else has been answering for more than a week and a half now i'll go with
surskit with the ability swift swim @ Wacan berry uses giga drain on seaking
rotom-h with the ability levitate @ passho berry uses overheat on foretress

Image courtesy of bulbgarden

Sorry but even that fails since Forretress's Sturdy prevents OHKOs. But I'll keep the game going anyway..

Gastrodon w/ Storm Drain @ Rindo Berry used Rock Slide! (and resisting Overheat)

Grotle w/ Overgrow @ Occa Berry used Wide Guard! (and resisting Giga Drain)

Overheat is not a OHKO move.

I think that he means that since we're assuming that the hit will knock out the Pokemon, and Forretress's ability Sturdy doesn't allow a Pokemon to be taken out in one attack, that Overheat wouldn't work, since Forretress would be left with at least 1 HP.

I was unaware that they had added the underlined piece of the ability in B/W. Regardless, Overheat is still super-effective against Forretress, so it's still a valid move. It doesn't matter if it would KO the target pokemon, just if it is a super-effective attack.

(assuming gastrodon and grotle were the last team)

Breloom with poison absorb@toxic orb(resisting rock slide) uses Mega drain on gastrodon!

Hariyama with thick fat@life orb (also resisting rock slide) uses ice punce on grotle!

Typlosion @ Blaze @ Charcoal used FLAMETHROWER!
Poliwrath @ Water Absorb @ Mind Plate used PSYCHIC!

resisting flamethrower Altaria @ charti berry with the ability natural cure uses air cutter
Resisting psychic Solrock @ passho berry uses earthquake
both must resist ground and flying

Aerodactyl @ Rock Head @ Focus Sash used IRON HEAD!
Bronzong @ Levitate @ Choice Scarf used ROCK SLIDE!

Ferrothorn with Iron Barbs @ focus Sash used Mirror shot!
Hippowdon with Sand Stream @ Yache berry used Fire fang!

No comment on my photo. unless they are good. BTW I did this in 15 minutes

resisting fire fang Altaria with natural cure @ Charti berry uses heat wave
Whiscash with anticipation @ rindo Berry uses icy wind

Milotic (holding rindo berry) uses ice beam on Altaria!!!
Kingler (holding Wide Lens) uses Guillotine on Wiscash!!!

sorry i dont know how to put a good pic on...

Probopass @ air balloon with the ability sturdy uses discharge
Foretress @ occa berry with the ability sturdy used Struggle bug

It does not matter who blocks whom as they both resist both

Hint:
only 23 pokemon work

Reshiram @ Turboblaze @ White Herb used Incinerate! (on both foes)

Nidoking @ Poison Point @ White Herb used Double Kick! (on Probopass)

Nuff Said.

Steelix w/ Sturdy @ occa berry used Earthquake!
Skarmory w/ Sturdy @ occa berry used Icy Wind!

Bronzong @ occa berry with the ability levitate uses earthquake

Rotom-W @ rindo berry with the ability levitate uses discharge
image courtesy pokesho.com

Zapdos w/ Lightening Rod @ Charti berry used Heat Wave!
Pinsir w/ Mold Breaker @ Occa Berry used Earthquake!

Don't worry Pokemon Strategy Game! I'll revive you!

w/ Keen Eye @ Charti Berry used Blizzard!
w/ Moxie @ Haban Berry used Incinerate!

@Bat Master: Lightningrod doesn't redirect Discharge, and unfortunately Pinsir doesn't resist Electricity.
@twisterturtwig: According to here, Occa Berry activates before Incinerate destroys it.

Targeting twisterturtwig's Pokemon:

Magmortar w/ Flame Body @ Shuca Berry used Thunderpunch on Pelipper!
Jellicent w/ Water Absorb @ Wacan Berry used Ice Beam on Salamence!

Sprites courtesy of The Cave of Dragonflies

Rotom-H @ Levitate @ Kasib Berry used Shadow Ball (on Jelli!)

Shedinja @ Wonder Guard @ Lum Berry used Mud Slap (On Magmort!)

PLEASE DONT DIE ON US!

a couple of clarifications I even though that is how i'd fight normallly I did not reduce the maximum damage done to bronzong that would be my 5th mistake
second Heat wave on a lightningrod zapdos is illegal 4th gen move +DW ability does not mix
but because I made the mistake first he avoids anything
I've done the reasearch this is not impossible but it is one of the hardest i have posted might even be the hardest

this will be vs. rotom H and Shedinja

Excadrill @ air balloon with the ability mold breaker uses earthquake
Skarmory @ occa bery with the ability sturdy uses rock slide
image courtesy to pokemon wikia
either can block either because excadrill has an air balloon
I repeat this is not impossible just really hard

hint: there are multiple approaches that can be taken a direct attacks with grass dual types that resist rock

Torterra + anything will work if the proper move is used
Bat Master: if you want you can take it back to single battle mode

I'll post a response in a few days if no one figures this out

Torterra @ Overgrow @ White Herb used Superpower on Excadrill!
Breloom @ Effect Spore @ Occa Berry used Spore on Skarmory!

@ Levitate @ Kasib Berry used Icy Wind!
@ Insomnia @ Charting Berry used Air Cutter!