When taming a mosa on mobile, I recommend that use use a soothing balm of any type, them use and prime meat or normal meat (not fish) the tame and ithy, they dont agro to them so you can use a cross bow and tranc arrows to knock it out while riding it. Make sure to clear the area first before putting th stuff on it , and dont forget to bring Scuba gear.
Center tip: as they have added the mosa to the center I've found the easiest way to knock one out is find one close to the bubbles get its Agro and swim in the bubble the mosa will get stuck and it can't hit you. Also this gives you unlimited oxygen and sanctuary from being attacked by anything else. ðŸ¤˜ðŸ¼