I know the plan was to have them evolve once they fought each other, but that's... a little too complex for me. What's more, we have two pokemon perfect for that sort of evolution that don't use it - Zangoose and Seviper!
Which got me thinking, what are people's thoughts on having Canileaf and Tundrolf evolve with the Rivalry Orb?
The sucky thing being that the sprite for Rivalry Orb is clearly a Zangoose and a Seviper. It might be confusing to have it be used for Canileaf and Tundrolf as well. Maybe a Leafeon/Glaceon-style "touch the Mossy/Icy stone" thing?
Based on what we have currently for the script, I think that there's only one Rivalry Orb. We may want to rethink that if more Pokemon will be evolving with it.
Otherwise, I was going to suggest doing something like Shelmet and Karrablast, but we won't have trading. Maybe something like Mantyke's evolution depending on Remoraid - they evolve if the other is in the party?
There is something to be said though about the loss of elegance though. I mean, you get the white shard from Jane (Normal type - Zangoose), and then the purple shard from Bella (Poison type - Seviper), and then put them together and that can be used to evolve them. Bringing Canileaf and Tundrolf into that feels a bit shoehorned in.