>>43752494they are unusable because they are extremely predictable and only work in tandem, meaning you don't get to comfortably switch around and use strats like protect
a savvy opponent would simply focus fire on alakazam and now you are down two mons, then would start to pivot around resistances to normal and coverage mons, or through the use of intimidators, and make your slaking hit like wet paper over the course of two turns.
and now slaking can't switch out because it would go back to truant. That means you are basically down two mons from the start.