@AshootingStar In reference to Arc-V, given that's the one I just read...
It's all dependent on what you're out to accomplish. Depending on how good the OC is as a duelist and romantic interest. Odd-Eyes itself actually does have ritual, fusion, synchro, and xyz monsters.
If Yuya is a better duelist initially to the point he's already qualified for the tournament in the Standard Dimension, you could turn the run up into a training arc and still use Mr. Smiley in this way.
Have scenes between Yuya and your OC training in whatever extra deck or extra methods of summon you want. Yuya could then apply those in the coming duel or the oc could if you don't want them to have learned all summoning methods right away.
Beyond that, if you're looking for inspiration on how alternate counterparts could be handled better, there's actually this great video by Spectube.
https://www.youtube.com/watch?v=V4OkgiB7wrw&t=4s
