Pokémon Prism Version is a new Pokemon game in the mainstream series, confirmed to actually be a split part of the ORAS timeline, taking place 10 years after the events of the Gold/Silver/Crystal of that timeline and showing how Mega Evolution, Primal Reversion and the newly-discovered Delta Mutation affect the Pokemon world.
The game primarily takes place in Kanto, Johto and the Sevii Islands after the events of Pokémon Black 2/White 2. A new pair of protagonists set out on their own Pokemon journeys, each seeking different things depending on what gender the player chooses: whereas the selected gender will be the playable character for the game, the boy character will seek to fill up his Pokedex and the girl character will seek to compete in regional contests.
This game will also feature the resurfacing Neo Team Rocket (now officially Neo!), with Giovanni taking the commanding position and the executives (Proton, Petrel, Ariana and Archer) taking a secondary position only to Giovanni. Players can also expect to see a few Anime-based characters, like Jessie and James, who appear as Elite Rocket Grunts.
Several new types are introduced as well, each with their own weaknesses, resistances and strengths.
A type that better represents most light-based, angelic and other Pokemon, including a source of raw power. It's strong against Ghost, Dark and Monster (primarily due to evil and demons losing to good), weak to Steel (reflection), Grass (Photosynthesis), and Sound (Light is faster, but Sound outshouts everything), and immune to Dark (because what good would darkness do if a Light could shine bright enough to eliminate it?).
This type often shows off the more intimidating side of Pokemon, usually to the more ferocious or beastly-looking Pokemon. It's strong aginst Fairy (Tinkerbell wouldn't last long against a Hydra, don't you think?) Dragon (sometimes Fire breath isn't enough) and Psychic (common fear), and weak to Light (evil losing and stuff) Steel (monsters end up getting slayed by swords) and Fighting (warriors take down beasts easily; look at Hercules).
This type is commonly known as the more Digital side of Pokemon, representing Pokemon like the Porygon family. It's strong against Steel (High-tech lasers VS Metal; Metal loses) and Cosmic (Space Shuttles conquered space, so score one for tech), and is weak to Electric only (you don't want your computer to short out, right?).
Finally, a better type for Exploud than Normal! As you might guess, Sound primarily focuses on most aspects of screaming, whistling and shouting and whatnot; it's strong against Light (again, sound outshouts everything) and Bug (bats usually use echolocation to collect food), and weak to Cosmic (no-one can ever hear you scream in space) Rock (Rocks can usually muffle noise in large numbers) and Bug (how about that, a weakness and a strength; mainly due to bugs communicating through sound).
This type better represents most of the flying Pokemon that don't have wings (like Rayquaza, Tornadus, Castform, etc.). It's strong against Flying types (birds can't fly in Hurricanes) Grass (trees falling with intense wind) and Electric (metagame needs to be balanced), weak to both Fire and Ice (hot and cold fronts screw up wind currents) and Cosmic (no air in space), and generally immune to Ground (Dirt vs wind? Come on!).
Ah, Cosmic. The type bold enough to go where no Pokemon has gone before. This type generally applies to most Pokemon rumored to have come from Space (like Clefable, Deoxys, and Dialga). It's strong against [and immune to] Sound (again no sound in space) and Wind (no air in space) and weak to Fire (the various stars and planets are made of Fire) and Water (water and ice were rumored to be found in several places in space).
Discovered recently by Professor Birch in the Hoenn region, Delta Mutation is a new process Pokemon undergo while holding a Rainbow Stone in battle; if a Pokemon holds a Rainbow Stone, their typing will change to that of which their regular type is weak to (i.e. Normal-types become Fighting, Grass becomes (randomly) Ice/Fire/Flying/Bug/Poison; double-types have their types changed to one weakness for each types: Water/Ice becomes Grass/Fighting, etc.). Rainbow Stones, while somewhat uncommon, can be frequently found in Kanto, Johto and the Sevii Islands' new Underground.
Terrains to Weather
Another new addition to Prism is the upgrading of the Terrain moves (Electric, Misty and Grassy Terrains) to fully-fledged weather conditions, with another new weather condition being added as well.
Voltage Storm - Electric Terrain's upgraded condition, the Voltage Storm lasts the usual 5 turns (8 with the new Static Rock) and gives several features during that duration: Electric-type moves are strengthened, Pokemon with the ability Levitate are grounded, and Pokemon that are not Electric, Ground or Steel or have the abilities Motor Drive, Lightning Rod or Volt Absorb will take slight damage each turn (1/16 of their HP). The added bonus is that Pokemon with Volt Absorb will gain HP slightly and Pokemon with Motor Drive will gain a Speed boost each turn.
Blossom Maelstrom - Grassy Terrain's upgraded condition, a Blossom Maelstrom is a Grass-type's best friend (it lasts 5 turns, 8 with the Mossy Rock) and for good reason: it heals all Pokemon by 1/16 their HP per turn, 1/7 for Grass-types, prevents status ailments on any Pokemon, and ups the power of Grass moves.
Enchanted Mist - Misty Terrain's upgraded condition, the Enchanted Mist is meant to boost a Fairy-type's power further: Fairy-type moves have a damage boost, special conditions (like Poison, Burn, Sleep; other effects like Spikes, Taunt, and such) are nullified, and the abilities Mummy, Iron Barbs and Rough Skin are negated. (Traditionally it lasts 5 turns, but with the Marble Rock it lasts 8.)
Nightfall - Nightfall is a strange new condition introduced by the eponymous move Nightfall; this condition enhances the power of Dark-type moves, makes the move Moonlight restore the entire HP bar (Sunny Day doesn't work for that anymore), and lasts 10 turns instead of 5. However, this condition is not only disspelled by other weather conditions, but it can be dispelled by any Light or Fire-type move.
Comet Blast - Cosmic-type, 100 power, 80% accuracy. 10% chance to lower Sp.A + Sp.D by one stage.
Ancestral Memory - Dragon-type, 150 power, 100% accuracy. Cannot be used again after first use unless user is switched out.
Spore Storm - Bug/Grass-type, 20 power, 50% accuracy. Power and accuracy influenced by spore/powder factors.
Triple Jab - Fighting-type, 75 power, 85% accuracy. 20% chance to freeze, burn, or paralyze the target; since Triple Jab is a technique that combines the power of Ice Punch, Thunder Punch and Fire Punch, the weaknesses of Fire, Ice and Electric-types also apply, but not the resistances.
Colored Flood - Unknown type, 60 power, 90% accuracy. High-critical hit ratio. Super-effective against every type.
(More Coming Soon)
New Berry Effects
Twelve berries are introduced, some returning from the past and others being new to the series:
The Eggant Berry cuts damage from one supereffective Light-type attack.
The Drash Berry cuts damage from one supereffective Monster-type attack.
The Nutpea Berry cuts damage from one supereffective Wind-type attack.
The Strib Berry cuts damage from one supereffective Cyber-type attack.
The Beteb Berry cuts damage from one supereffective Sound-type attack.
The Pumkin Berry cuts damage from one supereffective Cosmic-type attack.
The Loupacon Berry boosts a Pokémon's HP IV by two points.
The Taccor Berry boosts a Pokémon's Attack IV by two points.
The Patato Berry boosts a Pokémon's Defense IV by two points.
The Pammle Berry boosts a Pokémon's Special Attack IV by two points.
The Chark Berry boosts a Pokémon's Special Defense IV by two points.
The Aocac Berry boosts a Pokémon's Speed IV by two points.
Bellossom went from unnoticeable Grass type to health-recovering tank in Prism; not only is any Bellossom capable of learning the moves Giga Drain, Drain Punch, and Draining Kiss, but it has the new ability "Leech Drainer" which ups the power of any draining move by 1/3 its original power. Have it hold a Big Root and you have a health-draining vampire.
Believe it or not, Hitmonchan's improvement didn't stop with the Mega; not only does his newfound Mega prevent him from missing the target, he has the move Triple Jab, a Fighting move which can not only get a boost from Iron Fist, but is essentially Tri Attack in punch form: it has a 20% chance of inflicting Burn, Freeze or Paralysis (the percentages are stacked, btw).
Other than his ability to copy any move of any Pokémon (including Legendary Pokémon's signature moves), Smeargle wasn't considerably remarkable. Nowadays, he has a couple new features that significantly improve him considerably; not only does his new ability Painter give 10 extra power to his damaging copied moves, but at Level 90, instead of learning Sketch again, he learns the brand-new move Colored Flood, which can turn him into a team sweeper; Colored Flood only has 60 power, but will have a high (about Slash level) chance of a critical hit and will be super-effective against EVERY TYPE. Yeah. Someone just soared to the Uber tier.
Didn't think the letters would be improved huh? Well, it's a complicated way to improve them, but if you collect all 26 kinds of Unown, the next Unown you catch will be have the hidden ability Mystic Power, which maxes out all the stats for Unown the minute you enter battle. An instant stat maxing the second you enter battle.
Many people like to make jokes about this little guy being the best thing ever because it's so weak; those days are over. If a player is patient enough to raise one to Level 40, Magikarp learns the move Ancestral Memory, a Dragon-type move that does horrendous damage (150 power, 100 accuracy), but can't be used again as long as said Magikarp remains in battle. And guess what? Magikarp can keep that move when it evolves into Gyarados. Who's laughing now? Magikarp, that's who.
Usually, the Paras line only was useful for learning useless HM moves; but when Parasect reaches Level 20, it learns Spore Storm, an unpredictable Bug/Grass move (first ever dual-type move that gets STAB from Parasect's type). Although this move is only 40 power originally, its power is increased depending on how many Powder-related things are given to Parasect:
If a Spore/Powder-related move is known, the power is increased by 20 depending on how many it knows (+60 being the maximum)
If Parasect has the ability Effect Spore, the move's power is 1.5x the total value.
And if the item SilverPowder is held, the normal 50% accuracy is increased to 85%.
What, you didn't think that just Gen 1 and 2 Pokémon were getting all the improvements? Not likely. Bronzong gets access to a signature move at Level 50: the Steel-type special attack Resounding Chime (resisted by Soundproof), which hits all the opposing Pokémon with a loud chime that has a chance to sharply lower the defensive stats.