Beserker and regular Attack boost are treated as the same buff, despite having different symbols. I think it and elemental links are the main exceptions to the “same symbol rule.”
There are a few hero-specific ones like Cheshire Cat but they are rarely seen.
You can see here detail info about Overwritten status effect:
CCat does not have any attack status effect.
CCat does normal/standar defdown (just like grimm, wilbur, valen, etc), but only applied to opponent yellow only.
Usually it’s opposite status effects. For e.g. Boldtusk attack up buff overwrites Scartletts attack down ailment, and vice versa if used in reverse.
Aside from those it’s exceptions. Usually the reason for them seems to be for the sake of game balance. Brienne not stacking with most other attack buffs or ailments is one example of that. Another example is Athena not stacking with regular defense reduction ailments.
I created the topic that Jinbatsu linked so I wouldn’t have to memorize them myself haha the fourth column (Overwritten) shows the status effects that will overwrite it.