The last episode hasn't aired yet.
Phineas and Ferb find the alien named "Meap" in the season 2 episode "The Chronicles of Meap." P.S If you like Meap, also check out the season 3 episode "Meapless is Seattle." It is better (in my opinion) than the first Meap episode.
If you go to youtube look up Ben 10 alien force season 3 you will see diamondhead chromastone cannonbolt and more
you can find ben 10 alien force vilgax attacks for ps2 at gamestop and walmart
She technically died in season 3 episode 22 but you dint find out till season 4 episode 1.
first season episode 38-39
Season 8 Episode 15
Season 6 Episode 16, in the end of the episode
Season 4, Episode 18.
Season 5 Episode 1: Everything on the line Season 5 Episode 2:Red skies in the morning Season 5 Episode 3:Stay focused or die Season 5 Episode 4:Put up or shut up Season 5 Episode 5:Long haul short fuses Season 5 Episode 6:Deadline
you find out in season 2 in the season finale :)
i have not been able to find a site that has all the vids but u should try veoh or megavideo which have some videos. one site that i know have most of the vids is http://www.watch-ben10.com/ .try this http://www.watchben10.net/watch-ben-10-alien-force.html it has all episodes but they are on megavidio I've found that you can watch Ben 10 alien force episode 1 on www.watchcartoononline.com and then in the search column type in Ben 10 Alien Force episode Ben 10 Returns, and it will bring you right to it. Click on the "more" link at the desired episode, and then scroll down until you see the screen and click play. Warning though, this website has some advertisements for free games that are kinda annoying and some of them not so good. Also, this site only allows you to watch 72 minutes of video and then it will not let you watch any more for another thirty minutes, then you can watch more again.
Season 4 Episode 11