In-game, most competitive strategies are thrown out the window (due to your ability to over-level), so I would say don’t even waste baton pass on a Manectric. There are much greater moves for both to use like:
Plusle
Thunderbolt/Thunder
Hidden Power (Water, Ice, or Grass is preferable to fight ground types) / Thunder wave for ease of use
Agility/Charge/Rain Dance
Return (physical, maybe not preferred) / Double Team
Manectric
Thunderbolt/Thunder
Bite/Crunch (crunch is an egg move)
Return
Hidden Power (Again, water/ice/grass is preferable) / Thunder wave (easier to get/easier to use)
I don’t have a lot of experience with Emerald specifically, so pardon the move sets as they may be a little weird, but I do know that competitive strategies are useless in-game. Plus (pun intended), Plusle is borderline useless compared to Manectric in base power and movepool. Hope I helped!