Praseodymium and Neodymium.No, seriously, the "dym" part means "twin" which is like perfect for referring to a pair of related legendaries. The third version could be Promethium, with a cover legend based on the legend of Prometheus.
Elements number 59, 60 and 61.
Cool idea, I forgot to use elements from the periodic table.... But why did you choose these three elements specifically? Imo, the noble gases have much cooler names: e.g. Pokemon Neon and Pokemon Xenon.
Pokemon Ranger Mega
Pokemon Zearl and Zimand
Pokemon Rage Ruby Serene Shappire
Why not "Mega Ranger"? Sounds more natural.
Did you just get the names "Zearl and Zimand" by replacing some of the first letters of "Pearl and Diamond"? As in, for DP remakes? But why replace the it with "Z"" specifically?
Rage Ruby and Serene Sapphire sound good.
Okay, anyway, here's my next batch of names:
Main Series (things I think have a good chance of happening):
Pokemon Lightning and Thunder
Pokemon Wind and Lightning/Thunder
Pokemon Myths and Legends
Pokemon Hell and Heaven
Pokemon Monochrome and Rainbow
Pokemon Rise and Fall
Pokemon Adventures and Journeys (Third Version: Pokemon Quests)
Pokemon Fate and Destiny
Pokemon Earth and Sky
Pokemon Champions (random idea)
Pokemon Guardian and Protector (based on what we know about a Pokemon in Gen VII)
Pokemon Dimensions and Universes
Pokemon Sun and Moon
Pokemon Solar and Lunar
Pokemon Immortal and Invincible (Third Version: Pokemon Eternal) (Fourth(?) version: Pokemon 4Ever?)
Pokemon Transcendence
Pokemon Concrete and Abstract
Pokemon Ultimate and Supreme
Pokemon Flames and Waves
Main Series Remakes and (Pr)(S)equels:
Pokemon The Hero of Black/Ideals and The Hero of White/Truths (B/W prequels?)
Pokemon Dark Grey and Light Grey (B2/W2 sequels/remakes)
Pokemon Light Black and Dark White (or vice versa) (B2/W2 sequels/remakes)
Pokemon Radiant Diamond and Luminous Pearl (D/P remakes/sequels)
Pokemon Shining Diamond and Glowing Pearl (D/P remakes/sequels)
Pokemon Flame Ruby and Wave Sapphire (R/S remakes/sequels)
Pokemon Axis (or spell it like "Axys", and it could be the X/Y sequel/remake)
Side Series:
Pokemon Mystery Dungeon: Order of Life
Pokemon Ranger: Dragons of Tao
Pokemon Ranger: Swords of Justice
Pokemon Conquest 2 (obvious title for Conquest sequel)
Pokemon Snap 2 (obvious sequel to Snap)
Pokemon Island (Snap sequel/remake)
Pokemon Click (Snap sequel/remake)
Pokemon Discoveries (Snap sequel/remake)
Crossovers:
Pokemon Water/Fire/Earth/Air (Pokemon/Avatar/Korra crossover?)
Pokemon Galaxy (Pokemon/Mario Galaxy crossover?)
Pokemon Duels (Pokemon/Yu-Gi-Oh crossover?)
Pokemon Infinity and Beyond (Pokemon/Toy Story crossover?)
Other Random Ideas (Things that probably won't happen):
Pokemon Hot and Cold
Pokemon Yes and No
Pokemon In and Out
Pokemon Wrong and Right (few will recognize the Katy Perry reference)
Pokemon Front and Back
Pokemon Male and Female
Pokemon Heads, Shoulders, Knees, and Toes
Pokemon Bless and Sin
Pokemon More and Less
Pokemon High and Low
Pokemon Full and Empty
Pokemon Tunes and Melodies (Third Version: Pokemon Music)
Pokemon Symphony and Orchestra
Pokemon Night and Day
Pokemon Spring/Summer/Fall/Winter
Pokemon Hearts/Spades/Clubs/(Diamonds?) Or: (Pokemon Poker?) (Pokemon Cards?)
PokeMath:
Pokemon Addition and Subtraction (Alternative of "Plus and Minus")
Pokemon Multiplication and Division (I think you see where I'm going....)
Pokemon Sine/Cosine/Tangent/Cotangent/Secant/Cosecant (Pokemon Trigonometry?)
Pokemon Integrate and Differentiate (Pokemon Calculus?)
PokeChem:
Pokemon Electron and Proton (Third Version: Pokemon Neutron) (Sequels/Remakes: Pokemon Positron and Antiproton)
Pokemon Matter and Antimatter
Pokemon Dark Matter and Dark Energy
Pokemon Mixture and Compound
Pokemon Pure and Impure
Pokemon Organic and Inorganic
Pokemon Covalent and Ionic
Pokemon Metal and Non-metal (Third Version: Pokemon Metalloid)
PokeBio:
Pokemon Plants and Animals
Pokemon Homozygous and Heterozygous
Pokemon Cold-Blooded and Warm-Blooded (Or: Pokemon Poikilotherm and Homeotherm)
Pokemon DNA and RNA
Pokemon Vitamin A, B, C, etc.
Yeah, I should probably stop now....