Honestly in my opinion the kings of the sea, I've absolutely wrecked squids with my mosa, just hug the floor and you will glitch into the squid's head and it can't touch you, you on the other hand can bite it til its dead without taking any damage
How to get a high quality mosa saddle/mosa platform saddle on mobile:
Head into the yeti cave (tame one of the wolves in the cave to do this). In one of the big rooms there are multiple snow covered platforms. On one of the platforms is a red cave drop, and the loot of this drop includes mosa saddles and mosa platform saddles. I ran the cave ~100 times and I got 4 mosa platform saddles (1 journeyman 3 ascendent) and 2 mastercraft mosa saddles but I don’t even have a mosa lol.