Hey man, cool deck.
There is a fairly new card that I think could be really good here:
Sisay, Weatherlight Captain.
In a singleton format, being able to tutor for your pieces can be incredibly valuable. Your Planeswalkers tend to have a decent mix of colours and are all reasonably low CMC so getting them with
Sisay shouldn't prove too much of an issue.
Sisay's activated ability is incredibly strong too, allowing you to tutor and put it straight on the battlefield at instant speed, which combos amazingly with some of the new walkers from War of the Spark (Narset,
The Wanderer, even Tibalt). It can really shut down opponents plans. The ability requiring WUBRG to activate is also wonderfully symmetrical with Ramos ability to create double WUBRG, so activating Ramos could mean two walkers tutored for and onto the field at instant speed.
My friend runs a Superfriends deck with
Sisay at the helm and she does a lot of work.
One potential downside is that her ability wont count as casting spells, so it won't contribute towards "charging" Ramos up again, so depending on your strategies for the deck this downside might be too much, which is fair enough.
Either way though, I've seen first hand the power she can provide to a Superfriends deck so thought I'd share in case it interested you.
Whatever you decide, I hope you continue to have fun with it. Cheers.