The #1 thing that needs to be in TLC 3. At least make it as large and powerful as the mosa. Should have one of the highest attack dammages because scientists have proven that the megalodon has the most powerful bite of any living thing and is strong enough to crush a tractor trailer.
Wild mantas can be fairly hard to hit with a megalodon.Just keep your shark still and the manta will often swim in front of its head.the rest is easy enough.with a high level megalodon even 120 mantas only take a few hits
You can’t eat or drink underwater which makes healing or renewing your Fria Curry or Lazarus Chowder a problem - Megalodons can swim straight up and straight down unlike some other aquatic mounts and when surfaced, you can dismount and stand on them to eat or use healing tonics. With enough HP you can set them to passive and let them tank damage from a Megalodon while using your rifle to dart the wild megalodon for a faster KO. Always best to have a few sharks with you while exploring the oceans.