although ampharos has a good defensive movepool, it struggles to wall many top threats due to its fleeting number of resistances and lack of reliable recovery. forget about physical walling, it can't counter any common physical attacker except sub bu braviary due to its average defense stat. as a special wall, it is outclassed in almost every way by regice, who misses out only on fire-types such as charizard and heatmor, both of which still have a chance at 2hkoing it with fire blast after a tiny bit of prior damage. additionally, many defensive sets are easily taken advantage of by the numerous ground-types in the tier since they only carry an electric-type attack. heal bell alone isn't enough to warrant the use of defensive ampharos, let alone push it into a-rank.
offensive sets are generally done better by electabuzz or raichu, both of which have better abilities to use than static and more offensively inclined stats. ampharos will often find itself being killed off quickly due to lack of speed and significant investment in bulk.