How much does battle bond boost Greninja's stats (in gen 9)?

Question

Is it *1.5 or something else does it activate every time you get a ko do you lose the buffs after switching out does haze and clear smog work on it?

Answer 1

It works only once per battle.

It applies a singe stage boost to Attack, Special Attack and Speed when Greninja knocks out an opponent.

This would be a 1.5 times multiplier if none of those stats are boosted yet.

Battle Bond

They work like other stage based stat buffs and will be lost by switch ins or buff wipes.

Answer 2

[W]hen a Pokémon with Battle Bond directly causes another Pokémon (including allies) to faint by using a damaging move, its Attack, Special Attack, and Speed stats are increased by one stage. This ability only activates once per battle. If the aforementioned stats are already at +6 stages, Battle Bond will not activate.

As they're just stage increases, moves that clear stat changes will work.

Battle Bond (Bulbapedia)