u/piano_title

I played the game in classic mode with setmode and no items, so I'll give my review from that perspective. 

For me it strikes a pretty nice balance in this regard, especially in deciding when to give you access to certain Pokemon or items, ensuring that you probably won't be able to breeze through all of the fights, but you always have the tools to make a winning strategy. I am a bit sad that you unlock megas so late, but it's understandable.

I mostly like the mechanic of the different terrains but at times they aid your opponent WAY too much (Souta I'm looking at you with that infinite tailwind), and while you can also abuse this, it's a bit annoying to have to make a whole team for a specific fight so I tended to avoid that.

I love the whole thing regarding Rift Pokemon and how shields work and stuff, though the challenge can really be trivialized by just poisoning it because most of them don't clear their status after a shield break. Although I do like that they thought about the strategy of just bringing a whole team of Pokemon with destiny bond because it only works once, so props for that.

Regarding specific fights, the only ones that felt unfair at times were Angie, Souta and Spacea from the Main Story. Although Angie was mostly because I was being stubborn and I could deal with it once I decided to use that superstar Throh. For Spacea, aside from that completely busted mechanic of her stealing your Pokemon, I had the most obnoxious bug that made it so she didn't lose her shield at times. 

Some of the most fun I had with the game was all the planning I did to beat the "impossible fights" of the game, so I'll discuss each specific one and the strategy I used:

- Madelis (when you are Melia): This one is purely RNG and hoping for Togepi to get a boost from Ancient Power.

- Challenger Mercury (If you tackle it as early as you can): The jumpscare of Aqua Building. This one I first tried for a bit at trying to abuse immunities while setting up toxic spikes with Trubbish, but it was too reliant on RNG so I later simply caught Three Geodudes with Sturdy and gave them Oran berries so they could procc it twice (this requires them to be at level 1 with low IVs on HP).

- Deathwing Sonia: That moment you realize there are competent Team Xen grunts around when you first search Akuwa Town. This one I defaulted for using my Rare Candies to make my Talonflame learn Tailwind so that my three Drifblim could take one Pokemon each with Destiny Bond. I found their performance so goated in that fight I decided to nickname them after the Three Wise Monkeys. I found it disappointing that there wasn't much of a reaction other than a "..." after beating them, especially since we later learn that if they lose they are executed. 

- Madame X: This one was trivially easy by using a Drifblim with Destiny Bond and resetting until the Yveltal missed an attack, cause I didn't want to waste my Focus Sash (though I never ended up using it)

- The Xen Ship Overleveled Doubles Battles (again, if you tackle it as early as possible): This combination of battles was probably the hardest fights in the game. The first Doubles Battle I managed to get a win by using the move Wide Guard, Tailwind, Screens and having a low HP Sceptile to procc Overgrowth to get some important kills. 

The second Doubles Battle I relied on getting lucky with the amount of sleep turns I managed to get with my Breloom that knew Spore, while being able of oneshotting or near oneshotting most mons with I think abusing the power of Froslass with Aevian Froslass and an Alolan Ninetales that set up Aurora Veil. The most complicated part of this fight was the Alakazam which was dealt with by abusing the weird AI that happens with Zoroark.

For the final Doubles Battle I simply gave up and abused the forbidden combination of Shedinja with an Aromatisse with Skill Swap, which proceeded to set up with Calm Mind and kill the entirety of the team. The only possible pokemon that can deal any damage to you is the Kommo-o with Vile Assault, so if you manage to defeat that you are golden. 

- ADMIN: That unkillable Regirock fight. This one was simply a matter of poisoning it, setting up Leech Seed and then have my level 1 Geodude do whatever for over a 100 turns (teach it moves with tons of PP). Eventually the game tells you that it's just a waste of time and makes you auto-lose, but I still count that as a win. 

- The Ana and V Gauntlet: This one was extremely tough since I didn't know it was coming and I didn't want to take a loss so I couldn't build a specific team for this, but I eventually managed to find a way. My team at the time was: Primarina, Garchomp, Yanmega, Breloom, Aevian Froslass, Mawile. Breloom trivialized the first Ana fight by abusing Spore, Leech Seed and Substitute. 

Sadly the second Ana fight outspeeds and oneshots Breloom, so it's not possible to repeat this strategy. For the second one I took one of the shields with Mega Mawile tanking one hit, setting up a boosted Sword Dance and then using Sucker Punch. Then it was up to my Impulse Yanmega with Protect to be able to outspeed, then using a combination of Flash and Swagger while whittling away at it with Air Slash, then probably finishing it with another mon if Yanmega got hit.

Then the fight against V was I think using the Interceptium Z on Primarina to use that Aurora Veil-esque move, then having Aevian Froslass and Garchomp take it down. 

I'm not referring to the teams you fight in the nightmare realm, but rather which team I think the MC (paragon route) would have.

Here are my suggestions, trying to base it off from story relevance as much as possible while trying to make it balanced:

1- Primarina

As starter I'd have Primarina for two reasons. First I don't think there's any important character that uses one, and second because it's a fairy type which is the MC's mom's type. I also find Primarina to be quite good for most of the game, so it's also nice in that sense.

2- Talonflame

It's an incredibly good pokemon that will always be relevant due to that fast tailwind. I also think it's likely the first pokemon the MC would catch, considering you can catch it at the oceana pier and they'd probably be inspired to have one due to being saved by Tesla in her Talonflame. W adoptive mom tribute.

3- Froslass

Specifically the shadow snorunt you "indefinitely borrow" from that team xen grunt early on during the goldenwood fiasco. Personally this is the only shadow pokemon I bothered to purify and it ended up being pretty darn good. It pairs nicely for double battles and a fast destiny bond mon is always useful. As a bonus, I think it has one of the best shinys (shinies? shinyes?) in the game.

4- Luxray

Probably the most random pick in the list. Story reasons would be that you can get a Shinx in Chrisola Hotel, so it being an event pokemon is nice. Aside from that, I'm including it to have a Pokemon that can make use of a crest. It having intimidate and being able of using a stab Return is nice too.

5- Mawile

This one in my opinion is a lock-in 100% percent of the time. It is given as a farewell gift from your mom and it is stupidly strong when you get access to mega evolutions. An absolute powerhouse full of motherly love.

6- Meowstic

Another no-contest, getting the Espurr from Wispy Path is probably one of the most memorable and enjoyable things on this game. It is also quite useful if you get a male as you get access to Prankster screens, which is a necessity when there are so many hard-hitting enemies in this game.

HMs:

Arcanine, which you can get in a very similar fashion as Meowstic, but I didn't put because there's already talonflame to be the fire type and tbh I didn't enjoy getting it as much as the Espurr.

Sylveon, the one you get from your mom on one of the most wholesome sidequests. Unfortunately there's already too many fairy types and I never really found a reason to use it in the game.

Gardevoir you can get from the VGCR. A bit of the same case as Sylveon, just gets its role fulfilled by the other mons.

I'd like to include an Aevian pokemon but no idea, I only used Aevian Froslass because it hits like a truck in double battles with a full HP water spout and using it in conjunction with the normal Froslass makes for a nice visual.