I'll give it a shot, but I'm not quite as scholarly.

In OP's original battle, Ash is under a spell by the ice king, and lets say that the spell extends to his Pokemon in such a way that they can't be turned against ash himself.

The powerhouse on Ooo's side is really Jake, but he would have to be very strategic in his fight against the pokemon since anything he stretches out as is still only his skin, and thus just as vulnerable as anything (to cuts, fire, electricity and so on.) Jake handles Pidgeotto and Heracross pretty handily, but is in trouble with the other pokemon. Jake could probably handle Ash singlehandedly too. Keep in mind that Finn is at least as agile, if not more so, than Ash Ketchum.

Enter Flame Princess, who is capable of ...well, all of this. Bulbasaur and Squirtle are pretty much wrekt, leaving Pikachu and Charmander in the fight.

Marceline the vampire would probably drink the red out of charmander, and (using any one of her many vampire abilites) defeat him pretty handily. I don't think she's a match for Pikachu though, unless her TK powers allow her to hold him in place. If that's possible though, she could hold him down for someone else to knock out pikachu (probably jake.)

But the crux of the whole fight is Ice King, who has ash and his pokemon under control. And if anyone is a proper counter to the Ice Kings neer-do-welling, it would be Princess Bubblegum. She and lady Rainicorn would no doubt be able to stop Ice King before Ash + friends cause any lasting damage.

I don't believe the evolved pokemon stand a much better chance.

I would give it 9/10 Ooo.