Well Arceus is the pokemon "god" but everything has it's own weaknesses. (except sableye and spiritomb)
Of course some pokemon are definitively tougher than others, it really depends on what you want in a pokemon, weather you want a wall like steelix, a sweeper like Gengar, something to set up an entry hazard like Forretress or just something to get your stat's up like Shedinja/Ninjask, basically it all depends on your strategy.
dragonite
noo dont be obsured a wonder card is the rarest posibble card to be found it is the most treasured object in the whole of the pokemon world the only way you can earn suvh a powerful card is by beating charizard with magikarp on the pokemon black and white for the nintendo DS.
I know that there are 2 super rare ultra powerful Pokemon in the whole entire Pokemon world.Those Pokemon are Raquaza and Arceus, but what i know is that RAQUAZA is by far the most and i mean the most powerful ultra legendary in the entire Pokemon world.
i believe its Victini's V-create which has a damage of 180
all 5 pieces of exodius
well i,m not sure but the most powerful card I saw is the skeletel dragon
Arceus
In my opinion, the most powerful Magic: The Gathering white card is "Swords to Plowshares."
The most valuable Pokemon card in the Pokemon card series is the Pikachu Illustrator card. It is highly sought after by collectors and can fetch a high price due to its rarity and unique design.
Caterpie
i would have to say that would be Lugia Legend from the new heart gold and soul silver expansion. It can do 200 damage with its Elemental Blast attack (enough to knock out any Pokemon in the History of Pokemon TCG) and has 130 HP.
no its super nova the most powerful card in the game but with boosts i sugest its stormlord its storm lord