Lets see here:
Ampharos
Pros
- Respectable HP
- Good Sp. Atk
- Respectable Sp. Def
- Learns awesome moves like Thunderbolt, Discharge etc.
- Only 1 weakness - Ground
Cons
- Slow
- Available a little later than Grubbin, but still pretty early
Vikavolt
Pros
- Awesome Sp. Atk
- Respectable Def.
- Learns move like Thunderbolt through Move Reminders.
- Two weaknesses only, helped by the ability Levitate - Fire and Rock
- Access to Bug Buzz, an amazing Bug-type STAB
Cons
- Slower than Ampharos
- Stats are pretty meh outside of Special-offensive stats.
- Very frail without the help of any Speed-Boosting items/moves
Both are fine in a gameplay, actually - pretty much anything goes in-game.
If you want a bulky attacker, go for Amphy!
Ampharos @ Ampharosite/Anything else
- Thunderbolt
- Signal Beam/Dragon Pulse
- Filler
- Filler
If you want to take the risk in exchange of a hard-hitting fighter, go for Vikavolt!
Vikavolt @ Anything
- Thunderbolt
- Bug Buzz
- Agility/Anything else
- Filler
Hope this helps!