Who are the strongest characters? Here is the top 10 in my opinion:
10. Jercy Packson - Before the loss of his arm, I'd honestly say he was pretty weak. Williezk probably thinks I'm just saying that because I disliked his character, but almost all of his fights were won with help. The only fight where he's alone was really the Omega Apophis fight and he was killed during it! After the loss of his arm however, he turned into an awesome, Nemletneg-hating maniac. I like that. He still has a long way to go, but I can definitely see him getting higher up on this list.
9. Holly Jenkins - A former mercenary with a cyborg arm? Of course she'd be on this list!
8. Retep Silednas - I have missed a lot of the episodes he was in so I could be mistaken about how tough he really is, but he seemed to be really powerful. After all, he owned a giant organization and was able to keep leadership of it until the very end of it and still survived. Pretty epic if you ask me.
7. Xhoth Denes/Spike - I'd say Spike and Xhoth are about equally as tough (but said Spike would win against Xhoth in a fight because Xhoth wouldn't be willing to kill his childhood friend for his own survival). We have seen Xhoth get pretty lucky in a lot of his fights, but he wins a lot of them. Definitely one of the tougher characters.
6. Leod Gabsti - He's survived so much stuff. An attack of gigantic alien spiders with the loss of only his eye, being captured by Mailliw, hordes of zombies, the Dreaded Games. And guess what? He survived most of this on his own. That's pretty tough.
5. Omega Apophis - He's a cyborg robot who owned Jercy. He could probably still own Jercy after Jercy's new arm cannon even before he (he being the Omega Apophis) became a cyborg. Why? Because he's epic.
4. Belati Adjo - She's made of billions and billions of tiny little organisms. Killing her would take a while.
3. Mailliw the Bloody - He is pretty invincible, as we saw by his decapitation. I'd say it'd be easier to kill him compared to Khrelan, though.
2. Khrelan Galagat - She's almost invincible, too.
1. Natas and the other Mysterious Aliens - Natas is pretty much invincible. Mailliw could only beat the crap out of him because he didn't have all his powers. (fungus3 edit: The only thing stronger than the Mysterious Aliens is the Infection in Badass.)