I experience that while i was in random battle the ability mold breaker didn't work properly. like my druddigon had mold breaker ability and he was against keldeo but keldeo ability didn't fail , because i did dark type atk on him and still his atk stat raise .. so yes i request to fix this bug about mold breaker ability in battle .. thank you ....

Hello @Darknesskings!

 

Apologies for the issue but it is not a bug.

 

Mold breaker is not supposed to cancel every abilities.

 

As stated here : 

When a Pokémon with Mold Breaker uses a move, the effects of all Pokémon's ignorable Abilities are ignored for the execution of that move. (Ignorable Abilities are most Abilities that could potentially negatively affect the success, damage, or effects of a move if possessed by the target of a move or its allies.

 

Mold Breaker prevents a target's ability from affecting moves that the Mold Breaker Pokémon uses. It only affects abilities that change the power, accuracy or other effects of moves.

 

 

But here Keldeo ability is a own pokemon ability, if you get hit by a Dark Attack, it raise the ATK always.

 

You can find all the ability affected by Mold Breaker there 

 

Hope this clear your question.

 

Very Respectfully,

 

Zarachi