I finally had a chance to read this, and it was a nicely done mission overall.

I like the author's note pointing out the better sides of the fic at the end.

The assassination had good dramatic tension.

One minor problem I found is what's probably a missing word in "Ashton gets some toys he really shouldn’t have and/or break the laws of physics."

I'm intrigued to learn more of Liz's backstory. It sounds like she fell into Fire Emblem from World One, but has maybe lost a lot of her Earth memories? I'm looking forward to finding out what exactly went down in her life.

I'm amused that Chenille is a rabbit-man, but avoids the happy, friendly bunny stereotype by being so gruff and analytical. That made it even funnier to imagine him in the Lopunny disguise, especially at the end when he briefly mimed being one in front of the Ash replacement. I don't know about the Pikachu's Electric attack "breaking" a generated disguise, and it kind of feels like a missed opportunity to let Chenille defeat it in the Lopunny body, but oh well. Maybe next time.

I think you handled the skipping around decently enough. It was a lot of portal usage and writing charges to read about, but it sounds like the original fic didn't leave you much choice.

I like the way you portrayed the real Arceus, with the bold, underlined text to contrast it strongly against Farceus. I generally dislike Pokémon speaking, but I think it was the right choice in this mission, especially since Farceus was already speaking anyway.

Some errors:

"Chenille opened another portal, waiting for Liz to fly into before he did so.

That should be either "fly in" or "fly into it"

"'Oh just chance,' Liz tried to wave it off. 'Actually, there’s something I wanted to tell you,'"

The comma at the end should be a period, since the sentence ends with this dialogue. I recommend a comma between "Oh" and "just" as well.

"Liz came back from that trip with two sets of mega stones and keystones, and dropped them in the backpack before setting off to neutralize Professor Oak, Gary, Delia, and Richard."

"neuralyze." Autocorrect probably did this one!

Lastly, since no one else has asked, may I adopt Physic, please?

—doctorlit had to look up why Uxie's eyes were important, because he never played Diamond or Pearl

I really like how you conveyed the crushing sense of boredom to the poor agents. You also did a frighteningly good job of displaying the "oh shpx why is he doing that he's ten" and the maniacal bloodlust of the Stu.

The description of the badfic's atmosphere when the agents first go in helps make the experience feel real.

As for some other moments: to me, this misssion gives less of a feeling the agents are detached from the situation and more like the agents are actually at the scene. For example, when they had to run to make sure the canons didn't see them. (I edited this since I misremembered what actually happened in the mission. Sorry)

"So she skimmed. And kept skimming. And kept skimming." This sentence conveys the frustration really well.

When the Suvians were about to get charged, I like how Spoiler

Also, I find the way the Vulpix acted to be adorable.

Anyway, the mission is very nice to read!

...I'm part of the Ashton Succeeds At Everything (Except Being a Character) Club over on the Discord, and on your agents' behalf, ouch! The mission was everything promised; good writing, agents being tormented, screwing with time, the charges we've been over, and an awesome assassination.

Some spoileriffic praise

I'm looking forward to seeing more of your stuff, and to sporking more of Too Good To Be True: Kanto League Failures on the Discord!