Again this? You can use any pokémon there, since you avoid the most repetitive weakness and bad movesets, the pokémon I used there were:
Starmie:
Modest (hardy for palace)
Surf
T-bolt
I-beam
Psychic
Salamence
Adamant
Brick Break
Rockslide
Earthquake
Aerial ace
Metagross:
Adamant (Hardy or palace)
Earhtquake
Sludge bomb
Meteor mash
Shadow ball
Blissey:
Impish
Softboiled
Aromatherapy
Seismic toss
Counter
Starmie and Salamence I used in all the battles, sometimes I swaped Metagross with Blissey and vice-versa.
I´m now trying to beat it again with some UU pokémon, like:
Ampharos
Modest
Fire punch
Thunderbolt
Counter
Thunder Wave
OK! IHIH
For battle Pyramid ask Expert Evan, he´s Expert there.