Pokelego999

Mewtwo, Psychic Force: Boosts the power of Psychic Moves by 30%
Articuno (and Galarian), Frosty Glide: Makes Pokemon immune to entry hazards. Priority Moves will not affect the Pokemon.
Zapdos (and Galarian), Shocking Glide: Makes Pokemon immune to entry hazards. Status moves will not affect the Pokemon.
Moltres (and Galarian), Burning Glide: Makes Pokemon immune to entry hazards. Critical Hits have a higher chance of occuring.
Raikou, Thunderous Roar: Boosts Sp. Atk and Spd by one stage upon entry.
Entei, Burning Roar: Boosts Atk and Def by one stage upon entry.
Suicune, Rainy Roar: Boosts Def and Sp. Def by one stage upon entry.
Ho-oh, Luck Flare: Critical Hits have a higher chance of occuring, and no critical hits can occur on this Pokemon. Upon switching out, this Pokemon will recover HP.
Lugia, Hydro Scale: Negates all damage dealt by 30%.
Regirock, Rock Recovery: Restores 1/16 of total HP at the end of the turn.
Regice, Permafrost: Negates all damage dealt by Fire moves. Opposing Pokemon have a 30% of becoming Frozen upon using a contact move on this Pokemon.
Registeel, Iron Body: Negates all damage dealt by any attack except for Fighting and Ground type moves.
Latias, Psychic Commune: Makes all ally Pokemon unaffected by spread moves.
Latios, Psychic Commune: Same as Latias
Kyogre, Drizzle/Primordial Sea: Same as normal.
Groudon, Drought/Desolate Land: Same as normal.
Rayquaza, Air Lock/Delta Stream: Same as normal.
Azelf, Willpower Psyche: Boosts Sp. Atk by one stage upon entry, and boosts Sp.Atk by one stage upon defeating a Pokemon.
Mesprit, Emotion Psyche: Boosts Evasion and Speed by one stage upon defeating a Pokemon.
Uxie, Knowledge Psyche: Boosts Sp.Def upon entry and by one stage upon defeating a Pokemon.
Heatran, Lava Shield: Boosts damage by Fire moves by 20%. Any Fire Moves will be drawn in and nullified by this Pokemon in a Double Battle.
Regigigas, Start Up: Doubles Atk, Def, and Spd upon entry for three turns.
Cresselia, Good Dreams: Drains 1/16 of the opponents health when they are sleeping and heals this Pokemon by 1/16 of it's health.
Dialga, Time Pulse: Lowers all Pokemon's Spd by 2 stages upon entry.
Palkia, Spatial Reconstruction: Lowers all Pokemon's Def by 2 stages upon entry.
Giratina, Temporal Distortion: Turns the opposing Pokemon into the Ghost Type.
Reshiram, Turboblaze, same as normal.
Zekrom, Terravolt, same as normal.
Kyruem, Technofreeze, nullifies the abilities of the opposing Pokemon.
Virizion, Justified: Boosts damage dealt against Dark Moves.
Terrakion, Justified: Boosts damage dealt against Dark Moves.
Cobalion, Justified: Boosts damage dealt against Dark Moves.
Thundurus, Stormy Sky: Creates Thundering Weather upon entry.
Tornadus, Windy Sky: Creates Wind Storm upon entry.
Landorus, Abundant Sandstorm: Creates Sandstorm upon entry. Boosts Ground moves power by 20%.
Xerneas, Fairy Aura: Same as normal.
Yveltal, Dark Aura: Same as normal.
Zygarde, Aura Break/Power Construct: Same as normal.
Tapu Koko, Electric Surge: Same as normal.
Tapu Lele, Psychic Surge: Same as normal.
Tapu Bulu, Grassy Surge: Same as normal.
Tapu Fini, Misty Surge: Same as normal.
Solgaleo, Full Metal Body: Same as normal.
Lunala, Shadow Shield: Same as normal.
Necrozma, Prism Armor/Neuroforce: Same as normal.
Silvally, Multitype: Same as normal.
Regieleki, Transistor: Same as normal.
Regidrago, Dragon's Maw: Same as normal.
Spectrier, Grim Neigh: Same as normal.
Glastrier, Chilling Neigh: Same as normal.
Calyrex, As One: Same as normal.
Kubfu, Unseen Fist: Same as normal.
Urshifu, Unseen Fist: Same as normal.
Zacian, Intrepid Sword: Same as normal.
Zamazenta, Dauntless Shield: Same as normal.
Eternatus, Neurovirus: Increases attacks power by 30%.

Better Graphics
The base Wild Area has N64 Graphics, and while IoA and CT improved on their graphics, I still feel even then certain parts need graphical updates.
Better Environments
The base environments of the Wild Area are very scattered and merge together randomly. Making the world mesh together more naturally would be better. On top of that, the areas are very barren. Perhaps adding trainer battles, side quests, and items could prove useful in making areas a little less boring.
The Pokemon
The Pokemon themselves, as mentioned, just walk around after hopping out of the ground. Both are wrong. Pokemon should be there from the start, not just hop out when you're two feet away. The Pokemon should also be in places you'd expect. Like, Kakuna lying dormant in a tree, or Haunter trying to spook you by going in and out of walls in a Haunted House. The Pokemon should do things in their free time. Pokepark Wii: Pikachu's Adventure, 14 years ago, did this same thing. Pokemon could play together and talk to each other randomly when you weren't doing it. Seeing Pokemon recreationally doing things together would already improve them. Pokemon should also have various ways of engaging battle, to make completing the Pokedex actually feel challenging. Having to sneak up on bird Pokemon, or lay out Honey on a tree to attract Combee or Burmy would make things feel more realistic.