I apologize in advance if I got anything wrong
First off, the location being the purelake adds an interesting aspect to this fight. The Tai-Na and Shadow can only really be effective in the deeper portions of the purelake (being about 6ft). I’m not sure if the Tai-Na would actually be able to maneuver around but I’ll give it the benefit of the doubt. The Chasmfiend cannot maneuver well there, as it would be mostly submerged at 6ft and hamper the maneuverability quite a lot. The Shadow can help the Chasmfiend on shallow waters but would probably be the best in the deeper parts.
The humanoids is an interesting mashup. I’m going to assume that through some sort of connection they are able to understand each other, save for the Koloss who just goes into bloodlust. They also each have weapons respective to their cultures, so the inquisitor has an obsidian ax, Koloss has his sword, etc. The Aimians provide an interesting aspect. The Dysian Aimian provides a distraction with the flying cremlings, yet their ability to pierce any large beat’s skin would be minimal. The Siah Aimian would be slightly weaker than the listener, being mostly another soldier from what I understand. The Kandra would be the skill of MeLaan, skilled but not TenSoon levels. Typical Kandra Stuff, blessings of Potency and Awareness. The Inquisitor would be the greatest fighter. I’m going to say it is one of the ones with F-Gold plus mistborn powers of the time. The Warform listener would be important to knowing how to take out the Chasmfiend, which I shall now get into
First off would be the Chasmfiend. The listener would be able to inform them how to target the weak spots, where the listeners tend to target themselves. During this explanation, the Koloss, getting into a bloodlust, would try and take out the Chasmfiend and be killed, yet not before chinking the carapace on the legs first. The group would then be down the dumb Koloss, but have another body for their Kandra. Without the spikes, the Koloss would just be a lot of flesh and not much superhuman strength, but that muscle combined with the blessing of Potency would make for a fierce fighter. A combination of the Koloss-Kandra and Inquisitor would be able to take out many of the Chasmfiend’s legs, as the cremlign horde would help distract it from each of the real threats, attacking eyes and such. The Chasmfiend would fall as the shadow gets to the fight, being hindered by the terrain. The shadow would be an easier target than the Chasmfiend due to no carapace, yet still take up most of the Inquisitor’s metals. The Tai-Na would be stuck in the deep waters, and I do not believe that the Inquisitor without many metals could kill the Tai-Na simply by merit of size alone.
Overall Result: Draw. If you assume that the beasts don’t get many hits on the Kandra-Koloss or the Inquisitor, the humanoids would kill the Chasmfiend at most but have trouble due to environment against the Shadow and Tai-Na
Next fight: Ham vs Dalinar
Simple dueling ring, no fancy terrain. Weapons optional. Ham has about 1 minute of straight pewter at a regular burn, Dalinar 2 minutes of stormlight since pewter is generally stronger than passive stormlight. Win through either pin, knock out of either ring or consciousness. Sticking Ham to the ground does NOT count as a pin. Assume they are unaffected by any change in gravity from their norm.