Most valuable Pokemon?

A Hydreigon that I got from an egg. I always use it in the Battle Subway or PWT in BW/BW2 and it kicks ass. I transferred it to X a few days ago and now it's Lv. 100

 

An Event Genesect was very useful to me for getting through the game.

 

That Haxorus you get for completing the unova dex. Mine got a bad speed nature, but I sashed it and it crushed the Black Tower and PWT. And it still kicks ass now!

 

I was able to get a shiny Nobunaga's Rayquaza through a trade during Gen 5. I still have it on my game now and it's by far the most valuable, seeing as it was only available in Japan for a shortish period of time. Although, that shiny flawless Charmander I got is also pretty valuable now that I think of it...

 

My liepard was awesome, it was really fast and had good attack with comendabl defene. I used it in the elite four and it just murdered them. She was my first Pokémon that i caught in the region and she never left the team.

 

That Gible I got from completing the Battle Tower. Its in my Pokémon X now and is level 51.

 

I have to go with Metagross as well. It got me through some tough Online Battles.

 

Pretty much all the event Pokémon I managed to pick up that can't be replaced.

 

Probably this Garchomp I got from a trade - I always used him in the battle subway and during online battles. He was pretty strong and I trained him up to Lv.97 or something until I lost my charger.

 

I've developed this weird attachment to my Archeops that I got from the fossil in Black. idk if anything's special about the stats (haven't bothered to check) but it's saved my ass a lot of times, it learns Fly (very important) and Acrobatics (which is just an awesome move). It's got a pretty good movepool anyways and it can also learn Earthquake (my default powerful move). It still looks ridiculous though lol

All the supposed gen 5 events I got by trading in gen 6. They just sit in my bank like little trophies. The pkm that take me through the plot I always have more attachment to

 

Mines is my Seperior <3 i love it so much considering it's a snake too xD

 

This is quite tough for me to answer. I have had so many Pokémon that really helped me progress through the games without much difficulty. Some of the more notable ones are Chandelure and Galvantula in B/W2 as well as Darmanitan and Eelektross in B/W. Chandelure's extremely high special attack, Galvantula's ability to make every Thunder hit, Darmanitan's incredible power and Eelektross's weakness to none make them all valuable members of my teams.

 

I had this really cool shiny Scrafty that I got from a trade. It was super useful when I went against a lot of Pokémon since it's pretty strong and after everything else, it just looks cool.

 

Serperior, my starter who carried me through the entire team

 

BW mvps were Archeops and Samurott.

BW2 mvps were Samurott and Aggron. c:

Archeops carried me through the entire Dragon gym, even with only a sucky Sp. Atk stat and Dragonbreath. Aggron's just awesome, tanking several super-effective hits, and Samurott's my starter, saving me several times. <3

 

My most valuable Pokémon in BW would have to be my Zoroark, considering Zorua could only be obtained through an event. In BW2, it was my Japanese Magic Bounce Espeon, which I traded from my imported B2 over to my English B2 and used on my team. The shiny Haxorus is also kinda special, though I used Pokecheck to get the Pokémon in the Unova Dex that I hadn't yet seen.

 

My event Genesect was what really pulled through for me, saving me lots of hassle in the poison gym. Aside from him, my serperior and the volcarona that I later caught both were awesome parts of my team, sweeping Pokémon that were a few levels higher than them easily.

 

my shiny female bidoof i got from wondertrade, it's so moody. if you know what i mean *wink,wink*