A mana dork with haste is a plus. You can only use the mana for creature spells but honestly this may be okay. Harabaz Druid from Worldwake is tons better in Modern, as the Druid always produces at least one mana of any color to cast any spell. But for Standard purposes, the Savant should be fine, especially in a creature heavy deck, and certainly passable in Limited. You don’t have to even play the Savant in Allies for it to work. The haste is really the best thing about it, so it may have a chance to slip into Standard in the right deck (probably Allies).
5G for a 5/5 is OK. A Rally trigger that gives you an anthem until end of turn (+1/+1 to all creatures) is OK. At common, this is very okay. You won't be seeing this in Constructed, but at such a low rarity it was meant for Limited play, anyway, so who cares. Requiring only a single Green mana makes it pretty splashable, too, so if you just need a fatty to top off your curve, the Beastmaster is your guy. He’s a lot better with Allies, though - actually, a ton better.
The Stalwart with Converge is easily a 3/4 in a three color deck, something Allies tend to call for anyway. With +1/+1 counter shenanigans, it gets even bigger. It probably won't crack Standard, but potentially having a 3 / 4 for only 2G is definitely decent. In an Ally centric deck in Limited, this is definitely a strong pick. At common, it’s especially a good value.
As a mere 2/1 to begin with, the Warcaller seems fragile. But the +2/+2 boost her Rally trigger provides is the real deal. The Warcaller is easily a 4/3, and is so as she enters play, and possibly a 6/5 on some turns in a dedicated Ally strategy. This is definitely an Ally I want topping out my curve. She does require two Green mana symbols, which makes her a bit less splashable than some Allies, but her Rally ability is worth it if you’re going all in on Allies - which this set really wants you to do.
I might be grading the Green Allies a bit highly, as there are only four of them, and their high grade is mostly due to the fact that you don’t have to commit to Allies to play 3 out of the 4 of them. Beastcaller Savant is borderline Constructed playable, and all 3 others are good Limited plays. As far as Constructed is concerned, this batch is probably more like a C. Green isn’t the best color - that seems to be a relative tie between Black and Red - but it’s close.
Now that we’ve looked at all 5 colors, will the multi-colored Allies make or break the Ally tribe in Battle for Zendikar? We’ll find out.