ampharos is beast. Nobody else has mentioned this strategy, but I love it.
why anything else? STAB, 95 power, 100 accuracy?
idk about black and white and lower, but in black2/white2
it raises defense by 4 levels.
1. he has high sp. attack
2.metronome and move ability combo is killer!
3.good against all types in between of what he doesnt have.
no weakness to ground
So basically, I think this is the best setup. Thunderbolt is reliable with STAB and if you need to use it twice it'll do more damage the second time. echoed voice will wipe them out with two or three hits, and with the metronome and echoed voice ability you can basically wipe out every Pokemon that won't tank him or is ghost. Cotton guard is just amazing. If you want something else, I would try hidden power (Ice) because cotton guard will protect you from ground and them wipe them with hidden power.
Also if you want to try confuse ray instead of magnet rise or hidden power you can, but that's not the best option.