Imagine, for a moment, that characters like Finn or Marceline had to pick a Pokémon team. What creatures would you match them up with?
Here's one take by shorelle, and I think it's perfect.
Jake already sort of looks like Pikachu, ergo...
Finn X Pikachu
Marcelline X Mega Gengar
Princess Bubblegum X Wigglytuff
If you liked these, make sure to check out more of shorelle's work here -- you'll find out who would be paired up with Charizard if you do.