400 point game, I have four robots. Is it a theme team?

yes sir....

...as long as those are the only figures you have.

IE, some fifth guy without the robot keyword will break the theme.

huzzah! ANd those are the only four. I couldn't remember how it worked exactly anymore. Is it just 1 for every 100 points?

isn't it in the 301-600 range? With a generic keyword, you require 6 characters

1-300 points requires 3 generic or 2 named keyworded characters
301-600 points requires 6 generic or 4 named keyworded characters
601-900 points requires 9 generic or 6 named keyworded characters
+300 points requires +3 generic or +2 named keyworded characters

Yes, BigSoph is right.
The old rules were 1 for every 150 points (named), 1 for every 100 points (generic), so under the old rules that would have been a theme team.
But now it's done under 300 point brackets with esssentially the same requirements. So you'd need 6 generic keywords (robot) or 4 named keywords (X-Men, Atlantis, etc) for a 400 point theme team.

This is how I understand it to work as well. It was done to "simplify" the theme teams. It does cause a lot of confusion for many long time players thou. Many clixers i've played weren't happy with the changes, having lost theme bonus for some of thier favorite teams, but most have adjusted over time.

QFT

(It would have been a theme before the 2012 rulebook.)