Salamence: go for Dragon Dance, Aerial Ace, Earthquake, and Fire Blast\Dragon Claw\Hydro Pump, depending on whatever your brother likes to use.

Flygon: Earthquake, Return, some other physical moves, maybe Fire Blast\Dragon Claw, plus a Choice Band.

Kingdra: Surf\Hydro Pump, Rain Dance, Ice Beam, and Rest\Toxic, with a Lum Berry\Leftovers\Mystic Water.

Altaria: Rest, Haze, Toxic, Dragon Claw, Ice Beam, Safeguard, etc. with Leftovers. Choose your pick.

Latios: Calm Mind and whatever special attacks work best for you. Latios gets a lot.

Rayquaza: Some sort of Dragon Dance physical-oriented set. Probably one like Salamence's.