Raikou has better bulk, can get past Mega Venusaur with Extrasensory, can hold an item like Life Orb or Choice Specs (meaning it hits harder), has a boosting move in Calm Mind, can actually check Bisharp, and its base Speed lets it check Thundurus and Keldeo (which Manectric can't do unless it Mega Evolved earlier in match).
Raikou wishes it had Overheat or Flamethrower, which allow Manectric to get past things like Ferrothorn and Mega Mawile far more easily. Correct me if I'm wrong, but a Manectric that has already Mega Evolved is
much faster than Raikou, getting past Greninja and Mega Alakazam. Both have their niches, but Mega Manectric is still more useful, I feel, so the lowest I'd drop Mega Manectric is
B. I prefer to see it stay in
B+, however, as its utility is still quite useful.
I'll just be writing one more post regarding Mega Manectric and Raikou, each with their stronger and weaker points.
Mega Manectric
+ Fits easily and really well on many types of teams
+ Fantastic scout, hole puncher and late-game cleaner with 135 SAtk and Spe
+ Lightning Rod as regular Manectric bolsters its Special Attack by 1.5 and gives it a chance to sweep, especially if it carries Flamethrower for consistency
+ Intimidate and Volt Switch further aid its scouting abilities
+ Overheat and Flamethrower are absolute gems, hitting Pokémon such as Scizor, Mega Scizor, Ferrothorn and Mega Mawile
- Susceptible to Bisharp, potentially activating Defiant
- Has trouble getting past Mega Venusaur
- Average special bulk (70 HP/80 SDef)
Raikou
+ Can run a variety of sets depending on items
+ 115 SAtk and Spe are pretty great with boosting items
+ AV allows Raikou to check specially powerful threats
+ LO gives it some nice power, especially when coupled with CM
+ Has Extrasensory for Mega Venusaur
- Physically frail (90/75)
- Pressure is very limited in use compared to Intimidate
- AV is kind of a weak hitter
- Coverage issues
- Walled by Mega Scizor
- Faces stiff competition from Zapdos as a bulky Electric-type
Both
+ Fast, reliable Electric-types that are easy to fit on teams
+ Both find their use depending on the team's needs
+ Each has its own selection of targets it can beat to help the team out
+ Both look badass as fuck
- Walled by Tyranitar, Mega Tyranitar and Mega Charizard X
- Hippowdon says hi
I don't want to unleash another Mega Manectric-related shitstorm, so I rest my case.
Leave Mega Manectric in B+; if dropped, to B at lowest.