a while back i edited Isshin Kurosaki to say he had attempted to learn the final Getsuga but it got deleted within a few mins and had various people say 'We do not speculate'...
just looked on Isshins page as i just read the latest manga and wondering if this has been updated and found 'At some point, he attempted to learn the Final Getsuga Tenshō by facing his Zanpakutō Engetsu' but no where i have read states this so isn't this speculation? if not can you say where it has said this in the manga as i don't remember this and wondering if i missed it somehow.
the only time i rememeber Isshin mentioning this was wwhen ichigo was training to get it but a while back this wasn't good enough for this forum as evidance