Weakest nation

[Rytek]

Middle Age is pretty balanced. With the exception of Ashdod out-shining the other nations by a decent margin.
Ulm may not have any Sacreds, but Guardians will smash any sacred rush they will face early game. And Ulm's troops are more than good enough to expand without an awake SC. An early elephant rush is the biggest threat and depending on research level is countered easy enough. Ulm needs a rainbow for magic diversity and that is ok because of their other strengths.

[Quitti]

I beg to differ with the balanced part. In MA Pyth, Ashdod (like you said), R'lyeh (vs other water nations), Jotunheim, Shinuyama and maybe to a bit lesser extent Ermor are way above other nations, while Ulm, Machaka, possibly Man (haven't really played them), BL, Atlantis and Agartha are quite a bit below the average.

Also, guardians are good, but expensive-ish and not that good against indies that you'd recruit them nonstop in the early game, but vs. at least Ermor/mictlan they'll work wonders if they're using sacreds like usual. And while the troops are not bad at expanding, you can't get enough of them unless you luck out with some really good mountain/forest provs with easy indeps next to your cap. And one rainbow mage (pretender) will not make the difference Ulm needs, while it does/would do help the problems they have with diversity.