Barbarian: Sumo

The Sumo Wrestler is a classic archetype that was perfected by the Gorons. These earthy giants would make use of their great girth and size to challenge greater giants of larger size to contests of strength from which Gorons would often walk away the victor. These techniques have since been learned by the smaller folk, who imitate the weight and style of Gorons by a rigid lifestyle of building muscle and fat so that they become giant-like among their own kind.

Sumo's Might

At 3rd level, you know how to use Sumo style in combat. You gain proficiency in Athletics if you don’t already have it and can add twice your proficiency to grapple checks. You are also proficient in Unarmed Strikes. While not carrying a weapon or shield, the die value for the damage of your Unarmed Strikes is equal to twice your proficiency bonus (i.e. a proficiency bonus of 4 would be a d8) + your Strength Modifier.
You also gain the following features when you enter a Rage:

• When you hit a creature with an Unarmed Strike, you can make a grapple or shove attack as part of the same attack.
• You count as one size larger for the purposes of determining grapple checks.
• You do not suffer any movement penalty while a creature is grappled by you.
• When a creature grappled by you starts their turn, you can cause additional bludgeoning damage equal to twice your Rage Damage

Steady Mountain

Starting at 6th level, your unarmed strikes and grapple damage are considered magical for the purpose of overcoming resistance to immunity and non-magical attacks and damage.
Your mental discipline has made you sound of mind and spirit. You gain proficiency in Wisdom saving throws. If you already have this proficiency, you instead gain proficiency in Intelligence or Charisma saving throws (your choice).

Giant's Grip

At 11th level, you have expertly learned to maintain a creature within your grip regardless of whatever tricks they may know. When a creature you have grappled attempts to escape by succeeding on a skill challenge against the grapple, by using teleportation or through some other feature that avoids making a standard escape attempt, you can use your reaction to force them to make a Constitution Saving Throw (DC = 8 + your Proficiency Bonus + your Strength modifier). On a failure, that creature becomes Stunned until the end of your next turn and remains grappled by you.
You can use this feature a number of times equal to your Proficiency Bonus and regain all uses of this feature when you complete a long rest.

Wrestler's Fury

At 15th level, you are not deterred from fighting even while you have another creature grappled. You have learned to use your opponent as a weapon and a shield while dealing with other foes. While you are grappling a creature and are hit by another creature you are not holding, you can choose to forgo any non-psychic damage resistances you have and split that damage with the grappled creature instead.
You can also use the creature you are grappling as an improvised weapon. While grappling a creature, you can make an Unarmed Strike against a different creature within 20 feet by hurling the creature you are holding into the second creature. On a hit, both the target of the attack and the creature you are grappling take the same amount of damage from the attack and are knocked prone. When used this way, the grapple ends after you make the attack and the DM applies fall damage as needed.
Lastly, creatures have disadvantage on Saving Throws against Giant’s Grip while you are raging.