Raikou is not a good replacement for Keldeo because while both are fantastic, they do completely different tasks. Perhaps it would help if you gave an overview of your team?
Sure thing, with this team I just reached 1400 on SD.
Lopunny @ Lopunnite
Ability: Limber
EVs: 252 Atk / 4 Def / 252 Spe
Jolly Nature
- High Jump Kick
- Return
- Fake Out
- Ice Punch
Bisharp @ Life Orb
Ability: Defiant
EVs: 4 HP / 252 Atk / 252 Spe
Adamant Nature
- Knock Off
- Sucker Punch
- Iron Head
- Swords Dance
Ferrothorn @ Leftovers
Ability: Iron Barbs
EVs: 252 HP / 88 Def / 168 SpD
- Stealth Rock
- Leech Seed
- Power Whip
- Spikes
teleGOD (Clefable) @ Leftovers
Ability: Unaware
EVs: 252 HP / 252 Def / 4 SpA
Bold Nature
- Moonblast
- Flamethrower
- Calm Mind
- Heal Bell
Keldeo @ Choice Scarf
Ability: Justified
EVs: 4 Def / 252 SpA / 252 Spe
Timid Nature
- Scald
- Secret Sword
- Hidden Power [Ice]
- Hydro Pump
Rotom-Wash @ Leftovers
Ability: Levitate
EVs: 248 HP / 216 Def / 44 Spe
Bold Nature
- Volt Switch
- Hydro Pump
- Will-O-Wisp
- Pain Split