User blog comment:ZokeiR/Possible Grand Servants/@comment-28209103-20170422172711

Good guess, I'm raising Karna as grand Archer candidate. Originally Karna are a skillfull archer even better than Arjuna and his armory are way stronger than Wasabi candy. Alternatively Hou Yi who shot down 9 suns

For Rider the ancient bellerophon might be a good candidate. Maybe Noah or that dude from Enuma Elish and the requirement of Grand Rider is that they must have MASSIVE vessel.. Rama also fit this bill. The grand class are said to be Gaia defense mechanism so I think like Grand Caster who need to have certain foresight other class have similar unique requirement. Personally I believe the req are Saber : Must wield Excalibur. Extella reveal that Excalibur are the sword that repeal olympian long ago before the age of King Arthur. Lancer : dunno Archer : No idea, but I think it's ability to take down celestial body Rider : MASSIVE Vehicle to safe humanity. Caster : claivoryance to predict disaster Assassin : Agent of Murder, ability to inflict the concept of death to target. Zerker : Absolutely no idea..