Let's have a look at the new pokemon we got in third versions in the past.

>Yellow
No new pokemon

>Crystal
No new pokemon

>Emerald
Speed Forme Deoxys

>Platinum
Giratina Origin Forme
Shaymin Sky Forme
Rotom appliances (5 formes)

>Black 2 and White 2
Landorus Therian Forme
Thundurus Therian Forme
Tornadus Therian Forme
Keldeo Resolute Forme
Black Kyurem
White Kyurem

>Third version of XY
[footage not found]

>Ultra Sun and Ultra Moon
Dusk Lycanroc


B-but the other games, anon! Why not talk about the remakes? Okay.

>Fire Red and Leaf Green
Attack Forme Deoxys
Defense Forme Deoxys

>HeartGold and SoulSilver
Pikachu-coloured Pichu
Spiky-Eared Pichu

>Omega Ruby and Alpha Sapphire
Cosplay Pikachu
Mega Beedrill / Mega Pidgeot / Mega Slowbro / Mega Steelix
Mega Sceptile / Mega Swampert / Mega Sableye
Mega Sharpedo / Mega Altaria / Mega Glalie
Mega Salamence / Mega Latias / Mega Latios
Mega Lopunny / Mega Audino / Mega Gallade
Mega Diancie / Mega Rayquaza / Mega Metagross
Origin Forme Groudon
Origin Forme Kyogre