Who exactly are the other two bodhisattva images often found in antique shops, one riding on white elephant and the other on lion?

Samantabhadra Bodhisattva is the rider on white elephant, its

honesty and balance symbolizing the bodhisattva' s merit and virtue.

He is celebrated for the resolve and intent of ten great acts and vows,

in particular the ninth, Chapter on According with All Living Beings:

‘In all sickness and suffering, be apt healer,

For those amiss in practice, show the correct path,

In the darkest of nights, be the guiding light,

For those wanting and poor, lend control and cover.’

Vowing to enable all living beings to benefit, Samantabhadra

Bodhisattva is deemed Foremost in Act and Vow.

The bodhisattva atop lion—literally, pi-xiu, a legendary beast resembling

the lion but with dark green fur and regarded as most auspicious—is

Manjusri, teacher to the seven Buddhas, mother to immeasurable

bodhisattvas, and deemed Foremost in Wisdom.