Except one thing Lyfsaho. I DID do them right.
I'll break it down. I used Tail Glow (+2 Special Attack), I am holding a Life Orb (which was still semi-standard), and Timid (which I'd even question myself to use. If this thing was still OU, I'd use Modest for the extra power). 252 Special Attack EVs as well.
Ludicolo, Tentacruel, and Mantine had 252 / 252 Positive spreads. Trust me, I did it twice just to get it, and got the same results. Even so, a spread like that is rare, especially on Tentacruel and possibly Ludicolo. And I can't believe you mentioned Mirror Coat, which is RARELY used as a tactic. It's even more stupid how you go as far as using Mantine in the first place (sorry TheMantyke, I had to say it) to counter him.
I didn't exactly know the true EVs for CMKou (I think I did it with 252 HP) but your statement hurt you even MORE. How you may ask?
With the EVs you suggested, after 1 Tail Glow, Manaphy does 91.39% - 107.42% with Surf. That means I could just lay Stealth Rock and garuntee that OHKO. Without the Tail Glow Surf does 45.99% - 54.30%. If you don't understand what I am saying, it's this: RAIKOU IS NOT A COUNTER TO MANAPHY! Raikou will put a tear to Manaphy, but he can't switch into Surf without being left a big mark in him. And if in the ABSOLUTE WORST CASE SCENARIO that there is Sandstream present, Raikou has no way to recover whatsoever.