i consider it an honor and a privilege to be the 164st commenter.
unfortunately for everyone, these crest ideas are the best. you just can't do better than this lemme tell ya.
magikarp crest: magikarp can leap over mountains. splash is now a 250BP move that always paralyzes (due to the shock of being hit by a fish at mach 4.)
grimmsnarl crest: takes ur kneecaps
g-weezing crest: gives your character sprite a top hat
a-eggy crest: makes all pokemon on the field have a long neck
deliberd crest: each use of present gives you 2000P. happy birthday!
g-meowth crest: using payday summons Smauououoaouuauouag from LotR who then takes your money and incinerates the field
cresselia crest: hacks GF's servers to permanently change cresselia's name to "crestselia"
darkrai crest: upon equipping, loads up pokemon desolation in the background gyarados crest: makes gyarados water/dragon like it fuckin should be
sunkern crest: gets +6 in all stats upon entering battle. there will be no survivors. primarina crest: upon equip, changes all in-game music to Adele. "WE COULD'VE HAD IT AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAALL"
tropius crest: tropius now also grows oranges hydreigon crest: gives hydreigon a fourth head metagross crest: the X on metagross changes to a V and metagross can now use V-create
mega-ray crest: dragon ascent becomes dragon descent- rayquaza becomes ground/dragon and can only use dig
regice/rock/steel/gigas crest: with a full team of crested regis, they all fuze together to great a giant megazord (is that what it's called)
landorus crest: makes landorus stop existing
garchomp crest: kills you
magneton crest: erases your hard drive slowking crest: changes slowking's name to slowqueen. plays "we will (kings) rock you" on repeat
simisage/sear/pour crest: plays a random short from the Donkey Kong TV Show after every move
ninetales crest: gives ninetales a 10th tail aegislash crest: you now wield aegislash. if aegislash is shiny, Link now wields aegislash
polteageist crest: now also serves coffee
g-max eternatus crest: changes form to master hand. you are now playing Super Smash Brothers
sobble crest: through the power of tears, turns the field underwater. this field cannot be changed.
miltank crest: HE NEEDS SOME MILK throh crest: attacks now throw mario at your opponent
draco/arctofish/zolt crest: swaps the top and bottom of the opponent's pokemon giratina crest: makes giratina a giraffe snom crest: snom now wields aegislash
stonjourner crest: grants +6 culture and centers the world map
eiscue crest: gives eiscue 4 customizable hair styles sirfetch'd crest: aegislash now wields sirfetch'd
wooloo crest: rolls away malamar crest: flips the game screen upside down. using topsy turvy spins the screen a random number of times.
incineroar crest: deal 50% bonus damage to pokemon that are not in smash
keldeo crest: keldeo is now friends with grass, and takes neutral damage from it
cryogonal crest: deals additional scaling bonus damage based on your high score in Super Hexagon klink crest: deals double damage in Gearen City
escavalier crest: implements the weapon triangle: all sword based moves have 10 less BP and 10% less accuracy. all attacks against sword-based pokemon have 10 more BP and 10% more accuracy emolga crest:
cinccino crest: cinccino now wears each scarf you have in your bag. it's very fashionable.
mesprit crest: adds an "i" into its own name so it spells "mespirit" which is correct togekiss crest: your opponent can no longer attack
shaymin crest: punts posty
ambipom crest: automatically uses helping hand each turn budew crest: good choice. you win the game.
bidoof crest: displays a random prequel meme at the start of each turn jirachi crest: spoils the ending of reborn
wynaut crest: asks the opponent "why not". if the opponent does not respond, gain one extra turn.
kecleon crest: inverts color change. when using a move, become a random type that resists the move you just used lunatone crest: becomes Lunala
solrock crest: falls to ground, does not become solgaleo. go to jail
(that was @Kin9ofparadise's and i think it's great)
wailord crest: splash now has an effect depending on the field. uses any combination of surf, earthquake, avalanche, or rock slide as appropriate
delcatty crest: normalize now works like type-mummy. anything that makes contact with delcatty is now a normal type.
shedinja crest: you now take super effective damage from all moves permanently upon receiving this crest. get some better strats, dum dum
pelipper crest: pelipper opens its mouth to reveal dory. dory's fluency in whale summons wailord, who attacks twice with crest effect. pelipper has no other moves.
ludicolo crest: recieve a special item from the spinda cafe!
quagsire crest: battle ends cuz everyone's just vibin mewtwo crest: spilts into two mews. the fight is now in doubles. snorlax crest: all the opponent's attacks are ineffective unless they use a poke flute porygon crest: at the end of the turn, porygon disappears and is never seen again
chansey crest: egg bomb throws an entire a-eggy at the opponent.
lickitung crest: lick now has a base power of 120 and the effect of wrap. mlem.
politoed crest: summons the power of the mystic mungus
gengar crest: animates gengar's sprite like in pokemon stadium
seel crest: gives you the 14th gym badge
slowpoke crest: all attacks now work like future sight where they do damage in three turns
unown crest: hidden power now hits 5 times, with the 2-5th times being of a random type
ho-oh crest: alternate form- changes its name to "ho-ho!" and attacks with an army of stantler.
ducklett crest: steals your opponent's item. all sound based moves flinch your opponent.
diglett crest: diglett is now able to learn all kick-based moves available via move tutor.
oddish crest: attacks do double damage if you live in a place where marijuana is legalized
sandshrew crest: dig now hits twice in a single turn
pikachu crest: you are now worth $103 billion.
arbok/ekans crest: your player name is now spelled backwards
pidgeot crest: your first move is replaced with judgement and always deals super-effective damage
kakuna/metapod/silcoon/cascoon crest: harden now also applies endure.
squirtle crest: your opponent is now on fire. they are dying, squirtle.
zacian/zazamenta crest: zacian/zazamenta can now learn fling. fling has a base power of 1000 and hits both opponents. there is also a small black and blue imp on their back.
barraskewda crest: every arrow in the game is now replaced with barraskewda's pokemon menu sprite.
cinderace crest: all sound effects are replaced by the sonorous, relaxing tones of a vuvuzela
stakataka crest: begins a game of jenga with your opponent
kartana crest: folds your computer into a paper crane
cosmoem crest: cosmoem now his its own field of gravity. gravity is always in effect. dying to physical damage results in the opponent being hit by black hole eclipse
bruxish crest: bruxish's teeth now sparkle. this crest is sponsored by Crest
comfey crest: you and your opponent exchange friendship bracelets. the battle ends in a draw.
ribombee crest: streeeeeeeeeeeeeeeeeeeeeetch
gumshoos crest: no one really understands what you are or what you're doing.
avalugg crest: hitting a steel type changes the field to underwater
aurorus crest: aurorus now learns aurora veil and power gem come on gamefreak what the fuck it's right in the name
morpeko crest: you are worth $103 billion dollars in monopoly money.
florges crest: florges now also has grass stab, and its speed doubles in sunlight.
unfezant crest: unfezant becomes staraptor.
breloom crest: kicks you from the discord server
meloetta crest: seriously just let me use melo
virizion crest: you now get 5 bars of cell signal, regardless of location
cofagrigus crest: mummy now turns the attacking pokemon into cofagrigus
phione crest: turns phione into manaphy
probopass crest: adds disguise to probopass's abilities. pokemon that use thief/covet gain disguise and have groucho marx glasses added to their sprite.
ok. all crests are done. you're welcome, florida.
(ideas that might actually be useful are italicized)
seaking crest: the wrath of poseidon is called to rain down death upon your enemies. instant OHKO to mons weak to water.
meganium crest: the disrespect has finally trigged a powerful rage that buffs attack and special attack each time meganium is hit by a move. there is no limit to this. each stage over +6 adds 50% more to the relevant stat.
hitmontop crest: the accuracy of all hitmontop's moves is either set to 100% or 0% depending on whether you think the ending of inception is a dream or not. you are not told which is which.
popplio crest: popplio receives the signature attack "boop", which renders the opponent unable to attack for one turn.
sharpedo crest: sharpedo now explodes if an opponent makes contact.
luxray crest: luxray is now a dark type, and the AI now thinks you're 50% faster than you actually are. (i always think luxray is faster than it actually is. that's the joke.)
alcremie/swirlix crest: the opponent's biting attacks now heal hp.
cramorant crest: the cry of all flying pokemon in the game is replaced with the "moip" sound from finding nemo
sudowoodo crest: sudowoodo becomes an actual cut tree that only tells lies.
pupitar crest: in true bug evolution fashion, makes harden the only move pupitar can use
ampharos crest: beep beep you're a sheep. (getting this one is really fuckin hard)
q-rem crest: gives ice types rights
gardevoir crest: makes you a significant character in your favorite pokemon fangame
omanyte crest: once per battle, transform into arceus
greninja crest: turns greninja into yoshi. tongue based attacks add a random pokemon egg to your inventory
alolan raichu: using the move "surf" instantly wins the battle
oricorio crest: when fighting a ghost pokemon, dance moves will result in all active pokemon doing moves from Thriller
dialga crest: a random PMD song is now stuck in your head. you will never get it out. (and sky tower is now stuck in mine. fuck.)
dratini crest: the boss is pleased. you now inherit the "family business".
hatterene crest: all events in the game have a chance to be interrupted with a violent vibe check
blaziken crest: your attack always goes last
grovyle crest: absorb's base power becomes 80. opponents who lose to you in battle are sent to the slateport pokemon center.
arcanine crest: F
scizor crest: all your attacks are 4x more effective against kartana
kartana crest 2: all your attacks are 4x more effective against roggenrola
roggenrola crest: your name is really dumb. all game dialogue takes 20% longer to progress through because characters have to stilfle their laughter.
boldore crest: all your attacks are 4x more effective against scizor
tauros crest: Your balancing powers will be put to the test today when your desire to fight conflicts with your need to plan. You might be even more indecisive than usual as a result of this internal tension. Be aware of time and the restrictions that it puts on you. Devise a plan that uses your energy in the most efficient way possible. It's especially important for you to think before you act.
flareon crest: allows flareon to learn solarbeam
furret crest: furret gains the ability long reach
murkrow crest: murkrow faints three turns after entering the battle
girafarig crest: turns girafarig into giratina
qwilfish crest: just keep keepin it real, man
alomomola crest: upon entering battle, you hear a bidoof in the distance scream in horror.
kricketune crest: instantly defeat the second gym leader
glaceon crest: i like you.
spiritomb crest: after running from your past, it finally catches up to you. take 100 points of psychic damage. you know what you did.
gurdurr crest: if you are playing stakataka jenga, you can cheat.
krookodile crest: all your attacks are super effective against monkey-based pokemon.
scraggy/scrafty crest: you have deep pockets. all uses of fling hit twice, and fling does not consume an item.
zoroark crest: if illusion is broken by an attack that makes contact, the attacker takes 1/6th recoil damage for cutting themselves on dat edge