>>37494187Because they wanted it to be usable in official formats and battle facilities, but its ridiculous stat total would've made it overpowered. So, first they gave it a hindering ability in Slow Start, the idea being that is full power would only be available if you could keep it alive long enough.
Except they set the required time to FIVE FULL TURNS. Okay - difficult, but doable. Then they made Regigigas unable to learn Protect and Rest, rendering stalling impossible without a completely impractical amount of support. They then decided that Slow Start's counter would reset if Regigigas stopped being the active Pokemon for any reason. Regigigas never had a chance.
