Ferrothorn:
Ferrothorn looks pretty good. My issue is that if you want Ferrothorn to Start a Sweep, You must add Curse to the Set. If you decide to add Curse, your EV Spread also has to change. Here is what I recommend for a Curse Ferrothorn Set if you decide to run one:
Ferrothorn@ Leftovers
Ability: Iron Barbs
Sassy Nature:(-Speed +Sp. Defense)
EVs: 252 Sp. Defense, 148 HP, 110 Defense
- Curse
- Leech Seed
- Power Whip
- Gyro Ball
Here is what is recommended in a Curse Set. If you use a Curse Set on Ferrothorn, it means you can use Stealth Rock in it. Leech Seed can be replaced with Stealth Rock but not recommended.
Eevee:
Eevee, Lol. I recommend you run a Wish- Pass set seeing that it has Speed as its highest Stat. This is what I recommend for it:
Eevee@ Eviolite
Ability:Adaptability
Jolly Nature:(-Sp. Attack +Speed)
EVs: 252 Speed, 252 HP, 4 Defense
- Wish
- Attract
- Baton Pass
- Quick Attack
I think this is better xD! Eevee is too frail and too Weak to start a Sweep at all. Hopefully, this thing outspeeds to get an Attract in for you to use Wish. Quick Attack+Adaptability is wrecking STAB, for a nice Revenge Kill xD!
Hydreigon:
Nice Hydreigon, no suggestions here. Good job GT ;)
Pikachu:
I suggest Pikachu be a Special Sweeper only because you lack Special power. Here is what I recommend :
Pikachu@ Light Ball
Ability:Lightningrod
Timid Nature:(-Attack +Speed)
EVs: 252 Sp. Attack, 252 Speed, 4 HP
- Thunderbolt
- Hidden Power Ice
- Signal Beam
- Grass Knot
This should help you a bit more than a mixed Set. T-Bolt is STAB and hits hard. Hidden Power Ice covers its only weakness: Ground. Signal Beam and Grass Knot are Coverage.
I have no further suggestions on the Last 2, Good Luck on your Team :)