One console to have them all.......

http://en.wikipedia.org/wiki/Metal_Slug_%28series%29

Go down to the X-Box 360 section. All, except part 4 and
5 are listed. I don't know where they got their information.
A citation isn't listed.

All of em including 7 but personally I can live without 5 & 6 if I had to.

How about all of them, seriously why even release metal slug 3 in the first place. Release all the metal slug series like they did for the Wii. Just do it, but don't put  inifnite lives like in metal slug 4&5 (xbox), if not just sell the series one by one.