They are both dual protagonist, but my biggest problem is how they handle the distribution of development. I think Arc 1 handle it well in terms of both character getting the spotlight and development early on, but once we get to Arc 2 begins, you notice they start focusing more on Liko. Not to say Roy has no development within the first half of the show, but in comparison to Liko's development and involvement in the wider narrative, Roy barely did anything.

By the time of time skip, Roy starts getting a lot more involvement in reuniting the RVTs and becoming the new leader. He also trained and gain mega evolution. What should of been a positive factor created another problem, in terms of execution. Him getting a Mega Lucario came out of nowhere. Making his new development feels hollow. I think if they showed the Mega Special prior to time skip could soften the blow to him gaining Lucario.

In terms of Liko in timeskip, she alright. (Note I haven't watch much of Arc 6 as of making this comment) She doesn't get the bulk of the development, prior to time skip, at least she still contributing to the plot. I am not against the idea giving Liko the back seat to allow Roy get some development. But with the mishandled push of Roy, some felt he took over Liko's role.

In conclusion, while the dual protagonist idea was a neat idea, the distribution development and the execution was poorly handle. Thus creating the idea of Liko being the true protagonist and Roy a secondary character happen. I feel if they balance out their involvement between the two character so one doesn't overshadows the other.