Hi, This topic has possibly be posted elsewhere before but I thought i'd do a thing on it just so I can share my Two cents with everyone else.
I love double battles and normally trade all of my pokemon onto XD to get experience faster (from being traded and also fighting strong enemies when weak with a strong partner or using xp share) they level up really fast.
In the process I have also found some killer double battle combos that i thought i would share.
Heat Wave Sky Attack
this combo is great because groudon knows earthquake and can often kill both enemies in one hit anyway but also effects your partner as well which is why i team him with moltress since he is immune to earthquake with his flying type. Groudon's drought ups the power of fire type moves making moltress stronger and when moltress uses heat wave (high power high accuracy for power unlike hydro pump) and HITS BOTH ENEMIES
normally you can KO two pokemon a turn at least with this combo
Rain Dance Spark
Hydro Pump Rest
Water Spout Double Edge
Kyogre's water spout hits both enemies and with his drizzle powering up water moves it does loads of damage (but only at full health)
Raikou has alot of power when he uses thunder, the only problem with thunder is its accuracy but with drizzle active thunder always hits. If something knocks drizzle out Raikou still knows rain dance to put it back and support kyogre again. Not much is faster than Raikou as well and the only thing i have had avoid his thunder using this is a ninjask using double team.
Mega Horn (something)
Earthquake Scary Face
Fly Mind reader
Sheer Cold Ice Beam
This combo focuses on Articuno using mind reader and then sheer cold to KO in two moves. The aim is that he will kill any pokemon except those with the ability STURDY but most of these like golem are weak against ice anyway and can be KO'd by articuno's ice beam.
Rhydon makes the perfect partner for this combo for the following reasons.
1) can use earthquake without KO'ing artcuno
2) can take down types that are strong against articuno using above move)
3) has ability lightning rod which will take any electric attack aimed at articuno since he is weak against electricity, and rhydon is immune to electric attacks so nulls it.
I am experimenting with a few more combos that so i may very well add to this if i come up with something else that has high success rates or extreme power.
Anyone else have any Ideas for combos?
Hope this helps someone