Giant Beasts of Elbaph have the Haki that Tama lacks.
The question is: can Beasts with Haki break out of Tama's Mochi Fruit, like Law used his Haki to revert Doc Q's Fruit Ability.
It's possible in this case a Beast could still choose to take her side, if it liked her, though; as seen with Loki.
Loki befriending Giant Beasts is already foreshadowing Tama's Elbaph Beast Army; the real Beast Pirate Captain was Kurozumi O-Tama, the whole time.
If the Beasts on Elbaph are anywhere near as strong as the giant Snakes from Skypiea, Tama should have a fun arc, once we dip back to Wano for Pluton, then sail/teleport back to Elbaph again once Big Mom returns.