set up a spar with another big foe

Another day or two of training and you bring Betsy to a local gym. You find out one's been developed to accommodate various animorphs. Sturdier treadmills for whale girls, arctic showers for the penguins, etc.

Betsy comes from the locker room in her wrestling spandex, seeming pleasantly anxious about what you have in store today. “Betsy, we’ll have you fighting your first unofficial real match today. Some of the girls are looking to get into the league too, so they’ve been training around here and it was easy to find you a partner. This’ Helen,” you say, turning and patting the thick hide of a bare-backed anthro casually working on a punching bag.

Helen’s an elephant girl, some 6 feet tall, and plump and round all over. She has a small amount of blonde hair on top of her head, a trunk that hangs down around her own massive cleavage, and a butt you could park a truck in. Her short tail looks almost cute attached to the enormous rump. She wears jean shorts so small on her huge ass and thick thighs they’re almost pointless, and a pink tank top that houses her gray breasts. She smiles and waves cheerily, though Betsy seems a bit apprehensive. It may be bashfulness, or she may be a bit attracted to her fellow plumper. Or perhaps she’s jealous or intimidated.

“Helen’s been training here for a little while, and I thought you two could practice a match together today. See how you fare in the real deal.”
“Hiii,“ Helen chimed in a peppy voice, leaning in to hug Betsy excitedly. The sighs of their mammoth breasts pressing together stirs a tidal wave of thoughts in your head… and your pants. Helen has a similar attractiveness to Betsy. They seem about the same weight, though Helen’s is more focused in her hips.

“I hope we can both have a lotta fun today,” Helen says optimistically. “I’ve been waitin’ for somebody to pop my ring-cherry.” She giggles, and this seems to lighten Betsy up a bit.
“You girls ready for the ring, then?” you ask, stepping to stand somewhere between their line of sight.