I have been keeping an eye on this topic, saw a lot of good points on banning BPass as a whole as well as only removing stat boosts + passing, I'll try to not repeat (too much) stuff that has already been said and add my two cents.
In general, I think that banning stat boosting while preserving dry/sub/Wish passing would be a good start. However, is it really worth going for a complex ban at that point? The few 'mons that would benefit from such a thing that I can think of from that would be the Eevolutions, Durant, Shedinja and the main offender itself, Celebi.
On Durant it can act as a way to grab momentum, sure, but it can already hit most of his switch-ins pretty damn hard already
80% of the time with coverage moves, and the HC set wouldn't be able to pass boosts regardless.
On Umbreon/Vaporeon (sigh), usually Heal Bell is chosen over BPass. Granted, it is an option but there a somewhat limited amount of situations where it would be better over a different move.
Sylveon also gets access to Wish-passing, but drypassing on offensive sets is in my opinion the biggest thing about the whole argument. Sylveon hits like a truck, and has coverage to handle its switch-ins AND a somewhat surefire way to either keep momentum or do solid damage in almost every single situation against most teams.
Shedinja is already a pretty niche Pokémon as it is, losing BPass is another hit but ohwell.
Celebi would become a lot more manageable regardless, but keeping bpass means it has a potential way to get away from stuff without having to risk a more dangerous prediction, as well as the possibility of sub-passing. Again, sounds pretty niche.
In general, BPass makes stronger Pokémons even better by adding more safe options while being for the most part a niche on stuff that doesn't see as much use, and in both cases there would still be valid alternatives. Banning the move completely seems easier and would be my choice, since it also prevents stupid Ingran-pass shenanigans that might for some reasons pop up.
tl;dr banning bpass+boost is a good choice, getting rid of bpass just seems simpler since the stuff that uses it has valid options regardless
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on an unrelated topic, there is one reason why i think klefki is a terrible idea
In Gen 6, Klefki can learn Thunder Wave from:
- anywhere (all moves are level-up/tutor/TM/HM in gen 6)
no matter its positive perks, i really don't want to see a priority twave user. screw that. and screw twave.