I fully expect the 4th Gen remakes to be on Switch.
What I would like to see in the remakes:
Names: Shattered Diamond // Fractured Pearl
Lore:
Player has to stop Team Galactic, who is trying to control Time/Space but fails during their attempt, causing Dialga/Palkia to change form. Player then has to go around Sinnoh using tech stolen from Team Galactic to contain these Time/Space ruptures. Each rupture would have to be entered and would have a puzzle specific to each cover legendary: Timed puzzles for Dialga, mind-bender/perspective puzzles for Palkia. Gyms and Elite Four still exist, E4 not accessible until after Galactic story is completed.
Legendaries:
Due to Team Galactic's failed attempt to control Time/Space by trying to force Dialga/Palkia out of their realm, they fail regulating the energy field that creates the portal to pull the legendaries out, causing the legendary to overload with dimensional energy and break past their normal limits, causing Dialga/Palkia to get new forms: Shattered Dialga form and a Fractured Palkia form.
The forms change their respective types from Steel/Dragon // Water/Dragon into Steel/Psychic // Water/Psychic. However, to change up the usual style of gameplay, each get an ability that gives them the benefits of Dragon type (Broken Epoch // Splintered Void), making them essentially the first 3-type Pokemon (meaning they get STAB for all 3 types and weaknesses for all 3 types), and their signature moves get beefed up versions:
Roar of Time >> Time Fracture (Dragon) - Knocking out an opponent with this attack resets to your turn, entirely ignoring opponent priority status (abilities and all) and negates the next opponent's priority moves (including moves like protect/detect). This move is also treated as a Steel type.
Spacial Rend >> Space Shatter (Dragon) - Knocking out an opponent with this attack calls out a random Pokemon from your opponent's party, entirely skipping over the selection phase. Pokemon that got dragged out loses 1/8th total HP upon entry. This move is also treated as a Water type.
Arceus:
In turn, Arceus available in-game and gets a new form showcasing its 1000 arms. Arceus Creator Form. Arceus curls into itself and the ring around its waist detaches and turns into this aura that has the same protrusions as the physical ring and spins around the balled-up Arceus. The spinning aura gives the illusion that Arceus has 1000 arms. Arceus Creator Form loses weaknesses to every type, but also loses STAB for balancing purposes. Arceus only accessible when Dialga, Palkia, Giratina, Mesprit, Azelf, and Uxie are in party.
Post-game:
Post-game has Player going to 2 different realms: The Distortion World for Giratina and The Nightmare Realm for Darkrai. Distortion World should have a puzzle to reach Giratina, but the puzzle is based off a mechanic that relates to the opposite version's legendary. I.E In FD version you have to do a MC-Escher style mind-bending puzzle that relates to Distortion of Space, while in SP version you have to do a puzzle within a certain Time Limit that randomizes every time you fail/have to reset. The Nightmare Realm would have a puzzle to get to Darkrai as well, except the puzzles would be the same for both versions, it would just take mechanics from both. You'd have to do a mind-bending puzzle within a certain time limit or it would reset randomly every time you fail. You NEED to have Dialga/Palkia to enter Distortion World you NEED to have Cresselia to enter Nightmare Realm.
Pokemon:
A ton of gen 4, 5, and 6 get Megas, Lucario gets a second Mega since he's a poster-child for gen 4 and is hyper popular. All gen 4 and 5 starters get Megas.
That's a fairly comprehensive wishlist I would like to see. Even ONE aspect of the above listed would be awesome.