So Marnie dropping Morpeko as her ace for Grimmsnarl is really dumb, but what makes it even dumber is that it was so easily avoided. They didn't need to make a Gmax Morpeko just for her. They didn't even need to make her one of the only characters to vanilla Dynamax her ace (though that would have also worked). Just have her follow after her brother and not Dynamax anything.
Hm, I don't know, I think it works alright.
Consider that, before her Champion Cup battle with you, she never even used a member of the Impidimp family. It was a complete surprise... but that may be because we never battled her outside of a "friendly match". First time you battle her it's on the second visit to Motostoke and its just presented as a warm-up battle before facing Kabu. Second time you battle her it's to gain entrance into Spikemuth and it's more presented as a test; she does want you to not only gain entrance but also clear up this whole mess she likely feels partially to blame for by defeating her brother.
Because unlike Piers, Marnie does take battling seriously. It's her goal after all, she believes by becoming Champion she can shine a spotlight on Spikemuth's economic problems (which are implied to be partially Rose's doing due to Spikemuth not being in a Power Spot yet Piers refuses to move the Dark Gym). And so, in her belief, that also means she has to "play" by Rose's rules. If the only way to succeed in the Galar League is to use a Dynamax/Gigantamax Pokemon, she'll use one. It's not a matter of preference, it's a matter of what's most efficient to get to her goal. Therefore, in professional battles, that's when she uses her (Gigantamaxing) Grimmsnarl. Her not using it outside of the professional battles can either hint she doesn't see it as a preferred member of her team and Morpeko is her "true" ace, OR that she just takes battling so seriously she doesn't want to risk her "professional" ace to get hurt in a casual battle that it may not be able to battle when she needs it.
Eitherway, in a subtle way, it can point out the "error" in Marnie's thinking. Sticking to Pokemon's message that Pokemon are your friends and partner, by using Grimmsnarl as she is Marnie is treating it more as a tool. It doesn't matter if she's close to Grimmsnarl, at that moment in the story she's just doing what she believes needs to be done. And thus, when she goes up against the player who has bonded with all their Pokemon, her Grimmsnarl is defeated as well as her goal. But the thing is, her "goal" wasn't actually her "dream", and with it over she got a chance to re-evaluate what she truly wanted. And so when we next have a battle with her, a casual one in Spikemuth, she's now using Grimmsnarl as a true member of her party (also, if you battle her before doing the Galar Star Tournament, Morpeko and Grimmsnarl are both the same level).
Tell me what Galarian Ponyta typing again without looking up.
Cotton Candy-Type.
His team structure is just so annoying. And it wouldn't take that much to change things, just don't make him quite such a mono-type trainer. Toss an Eevee on there early on and have Bede complain about how long it's taking to evolve into an Espeon*, have 1 Psychic/Fairy mon on his team the entire game, maybe include 1 not-actually-psychic mon(not necessary to make this work but it's helpful) and shift the rest of his team when he switches types. There's no reason his final team should have 3 Psychic/Fairy types.
So initial fight: Psychic, Eevee, Psychic/Fairy
Final fight before swap: Psychic, (ghost or whatever), Eevee, Psychic/Fairy
Tournament fight: Mawile, (ghost or whatever), Fairy, Sylveon, Psychic/Fairy
Suddenly there's continuity across the fights since he only swaps 1 mon, he's still clearly a type specialist, but there's no type overlap beyond the minimum. What we got was just sad.
*Because he's a jerk
While I agree three Psychic/Fairy-Types feels like they're cheating, at the same time I kind of like that after switching Type Specialty he's forced to suddenly replace half his team. It's something I can totally see Opal enforcing, and heck, maybe Bede choosing to pick up a Gardevoir was in his own way rebelling against the complete overhaul of his team "
you may be able to force me to only use Fairy-types, but you can't stop me from using as many Fairy/Psychic-types as I can find; you're lucky Mr. Mime in Galar are Ice/Psychic!".
Infact, I'm wondering if that was maybe what they were going for, because outside of that, there's no reason for Bede to be a Type Specialist. Or why he wouldn't be a Steel-type Specialist as he respects Rose so much. Just because Marnie is a Type Specialist (and good reason to be) doesn't mean Bede also had to be; he could still have the Hatenna family as his Ace. Like if I made his team:
First Battle: Klink, Bronzor, Hatenna
Second Battle: Klink, Bronzor, Honedge, Hatenna
Third Battle: Klang, Bronzong, Doublade, Hattrem
Fourth Battle: Mawile, Galarian Rapidash, Mimikyu, Hatterene
Start him out with an even split of Steel & Psychic, Slightly tip the scale in Steel's favor, make his Steel-types look like they're coming along just before he's "betrayed" by Rose, and then FAIRY SWITCH UP!