[PortalTron]

I actually thought this up a few months back. While I am not sure if this would actually be the case, I think a combo of two Riders that are thematically and aesthetically similar would be best

Ichigo/Nigo - Pretty Obvious.

Kuuga/Agito - Since Agito was a sort of sequel (though not really) to Kuuga.

Build/Double - Pretty straightforward. Both combine two halves

Wizard/Ryuki - Both semi-Western-esque designs based on Dragons.

ZX/Geats - Similar designs as well as being original Rider-esque with their own
unique look

Zero-One/Black - Both were starts of new eras, and have a bit of yellow, red,
and black on their designs.

Den-O/Revi - Pretty obvious.

ZO/J and Decade/Zi-O or perhaps ZO/Zi-O and J/Decade or something?

Skyrider/Drive - Both had an unorthodox element (flying and Cars) while being
callbacks to Ichigo (or just generally Showa Era in Drive's case

Amazon/OOO - Both friendly, animal based Riders.

Super-1/Fourze - Both Space themed.

Stronger/Kabuto - Enough Said.

X/Saber - Both have the X design on their helmets, pull out a sword to
transform.

Kiva/Ghost ?- Spooky Riders. But also because both are specifically
Halloween-esque in their designs

Shin/Vice - An interesting one: Both are pretty organically looking, and
unorthodox riders.

V3/Blade - Seemingly an odd combo, but relatively thematically similar.

Riderman/Faiz - Both the fourth Riders of their era, and had more specific ties
to the villains of the series

Hibiki/Gaim - Aesthetically similar along with both having some of the most
Riders in a Hesei show

ZO/J and ZI-O/Decade seemed a bit obvious, but another option would be ZO/Zi-O, given that ZO was originally planned to have other Showa Rider powers. And you could have J/Decade because J literally turned into Decade in one of the movies.

Ex-Aid is the odd one out. Potentially with another Rider (maybe Gotchard?) but that's all I got.


naturally a Secondary Riders would have secondary Rider combos (which I came up with as well) and you could even have Dark Rider and Tertiary Rider combos and so on.