The banner aspect of this fight makes things even harder. Kenshin’s Gallade has a very strong two-square-long attack, and there’s no way to keep him from parking it on the banner near where it starts and remaining there. This wouldn’t be too much of a problem if not for the fact that Gallade, as a fully-evolved Psychic/Fighting Pokemon, has hefty defenses and the banner heals it each turn. Its offense certainly isn’t anything to sneeze at either, as it packs enough power to knock out most things that approach it at closer ranges in only two or three hits, even if their Link rating is comparable to its. This is why I advised Flying-attackers like Staravia with its Wing Attack and long-ranged attackers like Swadloon and Prinplup. Things that can attack at pseudo-diagonals with three-square-broad or similar attacks like Vine Whip (Pansage, Carnivine), Discharge (Flaafy), and Aqua Tail (Gyarados) are also important for this reason- since Gallade can’t attack at diagonals, they can pummel it from safety.
Your first concern here, of course, needs to be making sure that Kenshin’s forces can’t swipe all four banners. I recommend picking one of your two platforms and parking two of your Pokemon on it, so they can destroy anything that comes at them to take the banner there. This will prevent Kenshin getting an easy win, as advancing with all your Pokemon virtually ensures his ability to use the portals alongside Abra’s Teleport power will ruin you.
The Pokemon from the other platform would probably do best to ignore their banner and advance out into the Ether or through portals- but make sure you always send your sturdy team members through portals first, or you’re just offering a chance for a beatdown. Scraggy is especially good for this, with its immunity to the Psychic attacks that Kenshin’s Warriors use and its fairly sturdy HP/Defense combination.
While you’re afforded the first turn here, you should spend most of it launching one team across the field and preparing the other for the use of the portals. Once you’re set up and have ended your turn, it becomes Kenshin’s turn. He starts by declaring that he intends to “show [my] enemies the true meaning of battle- Kanetsugu!”
The named Warrior, Kenshin’s lieutenant, accepts the order, and the two make the opening move- Kenshin positions his Gallade on the banner near where it starts, and Kanetsugu moves his Drillbur onto the banner near it. This initial parking is very important- the two are the most defensively strong Pokemon available to Kenshin, and keeping them on the banners makes it much more difficult for you to capture the banners.
