The Legendary Pokemon available on Pokemon Prism rotate, but the requirements for them do not. Check here to see what you need for current or future Legendary Pokemon. More information on obtaining Legendary Pokemon can be found here.
Articuno: Have 10 Indigo (226--255 Hue) Pokemon and 10 Ice-types.
Zapdos: Have 10 Yellow (46--75) Pokemon and 10 Electric-types.
Moltres: Have 10 Red (346--15) Pokemon and 10 Fire-types.
Mewtwo: Have 10 Violet (256--285) Psychic-types.
Mega Mewtwo X: Have 10 Violet (256--285) Psychic-types and 10 Violet (256--285) Fighting-types.
Mega Mewtwo Y: Have 20 Violet (256--285) Psychic-types.
Raikou: Have 15 Yellow (46--75) Pokemon and 15 Electric-types.
Entei: Have 15 Red (346--15) Pokemon and 15 Fire-types.
Suicune: Have 15 Blue (196--225) Pokemon and 15 Water-types.
Lugia: Have 20 Colorless Pokemon.
Ho-Oh: Have 5 complete collections of pure-colored Pokemon each in one species (i.e., a rainbow of Absols).
Regirock: Have 20 Orange (16--45) Pokemon and 20 Rock-types.
Regice: Have 20 Cyan (166--195) Pokemon and 20 Ice-types.
Registeel: Have 20 Seafoam (136--165) and 20 Steel-types.
Kyogre: Have 15 Blue or Indigo (196--255) Water-types.
Primal Kyogre: Have 20 Blue or Indigo (196--255) Water-types.
Groudon: Have 15 Red or Orange (346--45) Ground-types.
Primal Groudon: Have 20 Red or Orange (346--45) Ground-types.
Rayquaza: Have 5 Green or Seafoam (106--165) Flying-types and 5 Green or Seafoam (106--165) Dragon-types.
Mega Rayquaza: Have 10 Green or Seafoam (106--165) Flying-types and 10 Green or Seafoam (106--165) Dragon-types.
Latios: Have 5 Blue (196--225) Dragon-types.
Mega Latios: Have 10 Blue (196--225) Dragon-types.
Latias: Have 5 Red (346--15) Dragon-types.
Mega Latias: Have 5 Red (346--15) Dragon-types.
Deoxys: Have 10 Red (346--15), Seafoam (136--165), and Violet (256--285) Psychic-types.
*Deoxys can be adopted in any of its four formes, but there is only one available.
Azelf: Have 15 Blue (196--225) Psychic-types.
Uxie: Have 15 Fuschia (316--345) Psychic-types.
Mesprit: Have 15 Yellow (46--75) Psychic-types.
Dialga: Have 25 Indigo (226--255) Dragon and Steel-types.
Palkia: Have 25 Magenta (286--315) Dragon and Water-types.
Giratina: Have 10 Red (346--15) Ghost-types and 10 Yellow (46--75) Dragon-types.
Heatran: Have 10 Red or Orange (346--45) Fire and Steel-types.
Cresselia: Have 20 Magenta or Fuschia (286--345) Psychic and Fairy-types.
Regigigas: Have 5 Rock-types, 5 Ice-types, 5 Steel-types, and 5 Normal-types.
Phione: Have 10 pure blue Water-types.
Arceus: Have 1 rainbow set for EACH Pokemon type and 20 Colorless Pokemon.
Tornadus (Incarnate): Have 10 Green (106-135) and 10 Violet (256--285) Flying-types.
Tornadus (Therian): Have 15 Green (106-135) and 15 Violet (256--285) Flying-types.
Thundurus (Incarnate): Have 5 Blue (196--225) and 5 Violet (256--285) Electric and Flying-types.
Thundurus (Therian): Have 10 Blue (196--225) and 10 Violet (256--285) Electric and Flying-types.
Landorus (Incarnate): Have 5 Red (346--15) and 5 Orange (16--45) Ground and Flying-types.
Landorus (Therian): Have 10 Red (346--15) and 10 Orange (16--45) Ground and Flying-types.
Cobalion: Have 10 Blue (196--225) Steel-types and 5 Yellow (46--75) Fighting-types.
Terrakion: Have 10 Orange (16--45) Rock-types and 5 Yellow (46--75) Fighting-types.
Virizion: Have 10 Lime Green (76--105) Grass-types and 5 Fuschia (316--345) Fighting-types.
Reshiram: Have 15 Orange (16--45) Fire-types and 15 Orange (16--45) Dragon-types.
Zekrom: Have 15 Blue (196--225) Electric-types and 15 Blue (196--225) Dragon-types.
Kyurem: Have 15 Cyan (166--195) Ice-types and 15 Cyan (166--195) Dragon-types.
White Kyurem: Have 15 Cyan (166--195) Dragon-types and 15 Red (346--15) Fire-types.
Black Kyurem: Have 15 Cyan (166--195) Dragon-types and 15 Indigo (226--255) Electric-types.
Xerneas: Have 5 complete rainbow sets of a Fairy-type.
Yveltal: Have 15 Colorless Dark-types.
Zygarde (50% Forme): Have 2 complete rainbow sets of a Ground-type and 10 Colorless Dragon-types.
Zygarde (10% Forme): Have 1 complete rainbow set of a Dragon-type and 10 Colorless Ground-types.
Zygarde (Complete Forme): Have 2 complete rainbow sets of a Dark, Fairy, and Dragon-type each.