A couple.
- Value-wise: Celebi Gold Star.
I use it in my Imakuni? theme deck because of the other 2 Celebi's that are close to identical to it (Neo Revelations and XY93). Celebi Gold Star is objectively awful, and one of the few cards who has an Ability (Poke-Power in this case) that DOES NOT SYNERGIZE with it's attack. It's attack wants more Energy on it to do more damage. It's Poke Power sacks all cards attached to it. It's so awful. I love it!
- Imakuni?'s Doduo (English)
I remember when this card first came out in Gym2 in Japan. Our card shop at the time got the Japanese booster sets in regularly, so you bet I was using tournament winnings to dump into boosters to get this thing (it was a white star chase rare). I never pulled it in the Japanese packs.
When I got back into the game in Christmas of 2016, I was shocked to see that they actually made this thing in English--I thought it was fanmade fake stuff. Nope. I bought 4 of them and made a deck with them instantly--I was also really happy that the English versions were super cheap compared to when I got 4 of them back in the day for about $50 a pop.
Now, for this next part you have to understand this: I have THE WORST pull rate of anyone here. I am the guy you buy booster AFTER because I am a magnet for the worst and lowest rares in any set. I could buy a sealed booster box and the highest rarity in any of the boosters would be Energy. That's how bad it is.
Cut to Christmas of last year, we went to my wife parents, as as a sort of "we know you like this, but haha, you're a nerd" gift, they got a 3-pack of Pokemon tins from Costco. And none of them had any boosters worth writing home about.
I wasn't expecting to pull anything neat or spectacular. But I was over the moon when I pulled Imakuni?'s Doduo ouf of the last tin. It's not in my deck, but it's going to stay in a toploader for a while. Ha!