A source (Smogon I believe) claimed that in the Japanese versions of Diamond and Pearl if Regigigas loses its Slow Start ability then the Attack and Speed drops aren't lost.
However, I tried the glitch with a Cherrim with Worry Seed and Regigigas so that Regigigas would be slower if Slow Start was active or faster if Slow Start wasn't active and it started to outspeed Cherrim after Worry Seed as if the Speed drop was lost.
Does the glitch actually exist in Japanese Diamond and Pearl or is there a hidden detail that I'm missing? I would love to check if it's possible to desync a link battle between Japanese/English Diamond and Pearl if it exists (though it'd probably result in a communication error).
Video of Slow Start glitch not working:https://www.youtube.com/watch?v=yySX9Umx44Q&feature=youtu.be
- With Regigigas as the leading Pokémonhttps://www.youtube.com/watch?v=w7rGHQSQSyc&feature=youtu.be
- Switching into Regigigas