We change one thing about a Pokémon, that would instantly make it go 1 or 2 tiers higher.
BUT, it has to be plausibe (fitting the Pokémon or something GF might do)
I'll start
Dragon Dance Garchomp
Shell Smash Salamence (through Shelgon)
Diamond Storm Physical to Special (Diancie)
Pic unrelated
+10 base speed to Durant. It would hit a vital speed tier and be able to outspeed key threats
>>26964464
+15 speed to pic related
>>26964596
It'll get a mega eventually
>>26964464
Crabhammer Mew.
Dragon Dance Groudon.
Nasty Plot Mewtwo.
Earthquake Entei.
>>26964464
give archeops moxie
Waterfall Seismitoad
Moonblast Togekiss
Heatwave Magnezone
Nasty plot Cosplay Pikachu
>>26964464
>Diamond Storm Physical to Special (Diancie)
Pretty sure this would make it get walled by blobs
If anything, it should get play rough and SD
Tri Attack Meloetta. Come on, now. Stab AND Serene Grace.
>>26964654
Not already having your event nasty plot mewtwo!
Contrary Mixed Attacker Mega Hydreigon.
Superpower and Draco Meteor.
>>26964464
Recover equivalent on Aggron.
Head Smash on Aerodactyl.
>>26964855
She can't use Nature Power?
>>26964464
We make that pic James regular design and retcon everything else about him and turn him into a turbo slut for Ash
>Masquerain is now Water/Bug
>Nasty Plot Gengar
>+30 HP to Munja
>Ditto Imposter : Now hit always first on Speed Tie
>Regenerator replace Flame Body on Moltres
>Magic Guard replace Snow Cloak on Aricuno
>Levitate replace Sturdy on Magnezone
>+100 HP in Zen Mode Darmanitan
>BUT, it has to be plausible (fitting the Pokémon or something GF might do)
...I got nothing.