Why isn’t Ampharos ranked?
Way too much competition over other Electric-types like Magneton, Rotom, both Raichu formes, and Eelektross. Ampharos's good SpA and capabilities as a slow pivot isn't enough when the meta has gotten much faster and stronger. Magneton, Rotom, and the Raichu's much better Speed makes them better as wallbreakers, Speed control (for Rotom and Raichus), and they all have better movepools and abilities to take advantage of their checks. Magneton, Rotom, and Raichu-Alola even have a secondary typing to give them additional offensive/defensive presence. Eelektross as a slow pivot/attacker completely outclasses it too b/c of Levitate, and better utility choices like Knock Off, Coil, and U-turn.
Ampharos probably isn't the worst thing you could use but it just doesn't stand out enough to be used over other Electric-types.