First of all, the method of use, press the T key in the game to open the input box. Then copy the following code into it and press Enter. Don't forget the slash in front - "/".
Minecraft mythical beast command encyclopedia How to summon the mythical beast in Pokémon MOD

Groudon
Then there are precautions. The summoned mythical beast may challenge the player, and it may be wiped out accidentally. Therefore, prepare more Master Balls. Just catch it and be done.
Minecraft Legendary Beast Commands How to Summon Legendary Beasts in Pokémon MOD
Charizard
Mew: /pokespawn mew
Mewtwo: /pokespawn mewtow
Grawo: /pokespawn Groudon
Rayquaza: /pokespawn Rayquaza
Zoroark: /pokespawn Zoroark
Charizard: /pokespawn Charizard
Blusto: /pokespawn Blastoise
Bulbasaur: /pokespawn Bulbasaur
Ninetales: /pokespawn Ninetales
Gargal: /pokespawn Marowak
Salamence: /pokespawn Salamence
Infernape: /pokespawn Infernape
Empoleon: /pokespawn Empoleon
Minecraft Legendary Beast Commands How to Summon Legendary Beasts in Pokémon MOD
Rayquaza
Leaf: /pokespawn Leafeon
Elf: /pokespawn Espeon
Umbreon: /pokespawn Umbreon
Steelix: /pokespawn Steelix
Cute Happiny: /pokespawn Blissey
Lizard King: /pokespawn Sceptile
Blazing Chicken: /pokespawn Blaziken
Aggron: /pokespawn Aggron
Cute Negative Charged Papa: /pokespawn Minun
Megalodon: /pokespawn Sharpedo