!catch

Alright then...

First i need to explain the variable you need to sue for this command to work.
it's ${random.pick}
the syntax for it is ${random.pick 'choice1' 'choice2' 'choice3'}

This means you will have to add every single pokemon from the list as a possible outcome.
fortunately theres a generator for this which ive used to generate a list from all pokemon from the first gen :D
Ive only generated the first generation.... (thats a weird phrasing) if theres any pokemon that are not on the list OR if you wanna create that list yourself use this generator and select the generations you want:
https://www.dragonflycave.com/resources/pokemon-list-generator?format=%27%25%5Bname%5D%25%27+&gens=1&order=alphabet

so the full variable would be:
${random.pick 'Abra' 'Aerodactyl' 'Alakazam' 'Arbok' 'Arcanine' 'Articuno' 'Beedrill' 'Bellsprout' 'Blastoise' 'Bulbasaur' 'Butterfree' 'Caterpie' 'Chansey' 'Charizard' 'Charmander' 'Charmeleon' 'Clefable' 'Clefairy' 'Cloyster' 'Cubone' 'Dewgong' 'Diglett' 'Ditto' 'Dodrio' 'Doduo' 'Dragonair' 'Dragonite' 'Dratini' 'Drowzee' 'Dugtrio' 'Eevee' 'Ekans' 'Electabuzz' 'Electrode' 'Exeggcute' 'Exeggutor' 'Farfetch’d' 'Fearow' 'Flareon' 'Gastly' 'Gengar' 'Geodude' 'Gloom' 'Golbat' 'Goldeen' 'Golduck' 'Golem' 'Graveler' 'Grimer' 'Growlithe' 'Gyarados' 'Haunter' 'Hitmonchan' 'Hitmonlee' 'Horsea' 'Hypno' 'Ivysaur' 'Jigglypuff' 'Jolteon' 'Jynx' 'Kabuto' 'Kabutops' 'Kadabra' 'Kakuna' 'Kangaskhan' 'Kingler' 'Koffing' 'Krabby' 'Lapras' 'Lickitung' 'Machamp' 'Machoke' 'Machop' 'Magikarp' 'Magmar' 'Magnemite' 'Magneton' 'Mankey' 'Marowak' 'Meowth' 'Metapod' 'Mew' 'Mewtwo' 'Moltres' 'Mr. Mime' 'Muk' 'Nidoking' 'Nidoqueen' 'Nidoran♀' 'Nidoran♂' 'Nidorina' 'Nidorino' 'Ninetales' 'Oddish' 'Omanyte' 'Omastar' 'Onix' 'Paras' 'Parasect' 'Persian' 'Pidgeot' 'Pidgeotto' 'Pidgey' 'Pikachu' 'Pinsir' 'Poliwag' 'Poliwhirl' 'Poliwrath' 'Ponyta' 'Porygon' 'Primeape' 'Psyduck' 'Raichu' 'Rapidash' 'Raticate' 'Rattata' 'Rhydon' 'Rhyhorn' 'Sandshrew' 'Sandslash' 'Scyther' 'Seadra' 'Seaking' 'Seel' 'Shellder' 'Slowbro' 'Slowpoke' 'Snorlax' 'Spearow' 'Squirtle' 'Starmie' 'Staryu' 'Tangela' 'Tauros' 'Tentacool' 'Tentacruel' 'Vaporeon' 'Venomoth' 'Venonat' 'Venusaur' 'Victreebel' 'Vileplume' 'Voltorb' 'Vulpix' 'Wartortle' 'Weedle' 'Weepinbell' 'Weezing' 'Wigglytuff' 'Zapdos' 'Zubat'}


So what you want to do is go to your streamelements command dashboard (https://streamelements.com/dashboard/bot/commands/variables) and click +NEW COMMAND and hit "Show Advanced" at the bottom.

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Trigger: !catch
User Level: Subscriber
User cooldown: <cooldown in minutes> (5 Hours is the max cooldown)
Command Cost: <leave empty>
Response: ${user} just caught a wild ${random.pick 'Abra' 'Aerodactyl' 'Alakazam' 'Arbok' 'Arcanine' 'Articuno' 'Beedrill' 'Bellsprout' 'Blastoise' 'Bulbasaur' 'Butterfree' 'Caterpie' 'Chansey' 'Charizard' 'Charmander' 'Charmeleon' 'Clefable' 'Clefairy' 'Cloyster' 'Cubone' 'Dewgong' 'Diglett' 'Ditto' 'Dodrio' 'Doduo' 'Dragonair' 'Dragonite' 'Dratini' 'Drowzee' 'Dugtrio' 'Eevee' 'Ekans' 'Electabuzz' 'Electrode' 'Exeggcute' 'Exeggutor' 'Farfetch’d' 'Fearow' 'Flareon' 'Gastly' 'Gengar' 'Geodude' 'Gloom' 'Golbat' 'Goldeen' 'Golduck' 'Golem' 'Graveler' 'Grimer' 'Growlithe' 'Gyarados' 'Haunter' 'Hitmonchan' 'Hitmonlee' 'Horsea' 'Hypno' 'Ivysaur' 'Jigglypuff' 'Jolteon' 'Jynx' 'Kabuto' 'Kabutops' 'Kadabra' 'Kakuna' 'Kangaskhan' 'Kingler' 'Koffing' 'Krabby' 'Lapras' 'Lickitung' 'Machamp' 'Machoke' 'Machop' 'Magikarp' 'Magmar' 'Magnemite' 'Magneton' 'Mankey' 'Marowak' 'Meowth' 'Metapod' 'Mew' 'Mewtwo' 'Moltres' 'Mr. Mime' 'Muk' 'Nidoking' 'Nidoqueen' 'Nidoran♀' 'Nidoran♂' 'Nidorina' 'Nidorino' 'Ninetales' 'Oddish' 'Omanyte' 'Omastar' 'Onix' 'Paras' 'Parasect' 'Persian' 'Pidgeot' 'Pidgeotto' 'Pidgey' 'Pikachu' 'Pinsir' 'Poliwag' 'Poliwhirl' 'Poliwrath' 'Ponyta' 'Porygon' 'Primeape' 'Psyduck' 'Raichu' 'Rapidash' 'Raticate' 'Rattata' 'Rhydon' 'Rhyhorn' 'Sandshrew' 'Sandslash' 'Scyther' 'Seadra' 'Seaking' 'Seel' 'Shellder' 'Slowbro' 'Slowpoke' 'Snorlax' 'Spearow' 'Squirtle' 'Starmie' 'Staryu' 'Tangela' 'Tauros' 'Tentacool' 'Tentacruel' 'Vaporeon' 'Venomoth' 'Venonat' 'Venusaur' 'Victreebel' 'Vileplume' 'Voltorb' 'Vulpix' 'Wartortle' 'Weedle' 'Weepinbell' 'Weezing' 'Wigglytuff' 'Zapdos' 'Zubat'}!  Congratulations!

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Example:

Alolagardevoir: !catch
Aquana: Alolagardevoir just caught a Magikarp! Congratulations

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After a user wins a pokemon you can give them the avatar for it using
!give <name> avatar <avatarname> (e.g. !give AlolaGardevoir avatar Magikarp)

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Before you st this up make sure to set all avatar prices in the streamavatars shop editing to -1 so people cant actually buy them but have to get them using !catch

Thats pretty much it... have fun ^