Under the current rules (as of writing this blog post) both of them would simply die as a state-based action due to the planeswalker uniqueness rule, so nothing special happens
Ill be honest, in our current metagame, Emboar doesnt have a place In a future metagame, it could be one of the most powerful cards in the metagame
Psychic Set #269 Art by AKIRA EGAWA View card details Rank #4 Mew V Ultra Rare #251 $98.00 TCGplayer Ranked #4 in the set, trading at roughly 12% of the top card's price
There is an obvious theme of utilizing cards from the new set that have the Undergrowth mechanic to build a sweet creature deck

This bingo card has a free space and 41 words: Catch a Shiny Pokemon, Do a Raid, Catch a Normal Type, Hatch an egg, Catch a new pokemon for your Dex., Battle a Team Go Rocket member, Catch a Grass Type, Look at the news, Accept a gift from a friend, Evolve a pokemon, Activate an incense/lure, Battle a real-life player, Complete a field research task, Catch a Water Type, Expand your storage, Catch a Fire Type, Get a new medal, Complete a special research task, Use a rare candy, Send a friend a sticker, Get something from the shop, Add a friend, Catch a Electric Type, Take a picture, Use a berry, Catch a Rock Type, Catch a Ground Type, Catch a Steel Type, Catch a Fighting Type, Catch a Flying Type, Catch a Psychic Type, Catch a Fairy Type, Catch a Poison Type, Catch a Dark Type, Catch a Ghost Type, Catch a Ice Type, Catch a Bug Type, Catch a Dragon Type, Spin a PokeStop, Feed a pokemon a berry and Train against a leader

However, the card more than makes up for this by having a lot of ability options and attack effects