I believe that now Coby is at least mid trio level. After all, Coby has had the greatest growth rate out of anyone in One Piece. Not even the Straw Hats can compare. In the beginning, he was literally a weak little kid who could do absolutely nothing. But in less than a years time, with training from Garp the Fist, he was strong enough to not only learn soru but also be called to the War at the Summit which only elites are allowed to enter. And now only Zoro trains in the SH's, the rest just chill and wait to rock up at islands. But Coby is still most likely training with Garp and fighting NW pirates.
He alsoawakened Color of Observation in which he'd have two years to hone.
And if Luffy can learn the basics of CoA with a teacher as Rayleigh. It's almost guaranteed that he'll learn CoA with someone who is stronger than Rayleigh. Plus, on top of all this, I believe he'll be a rokushiki master.
And this is why I believe he'll be the Garp to Luffy's Roger.
As for Helmepoo, IDK about him but I'll like it if he eats a mythical zoan fruit or some logia fruit which can help him with swordsmanship.