The Super Saiyan (actually kinda balanced tho)

You gain the abilites of a super duper saiyan

Ki Abilities - 3rd Level

Instant Transmission- As a bonus action you spend 1 Ki point to teleport to a location you can see within 50 feet, this does not provoke opportunity attacks

Ki blast - You gain a new attack option that you can use with the Attack action. This attack is with a range of 30 feet. You are proficient with it, and you use your Dexterity modifier to its attack and damage rolls. It deals radiant damage equal to your monk die.This special attack can be used for any of the attacks you make as part of the Attack action.

Kamehameha - You spend an Action and Bonus action to charge your ki

You spend 3 or more ki points and hurl a blast in a 100 ft line, creatures must make a dexterity saving throw (DC-10+Proficiency+dex) on a failure the creatures take 1D10+1 radiant damage for each ki point spent , half on a success

The player can also use their movement and spend 2 ki points to instant transmission before releasing this ability, gives the first target disadvantage on their saving throw

Kaioken - 6th Level

You may use your bonus action to use the Kaioken technique.

While using Kaioken, you gain the following benefits:

• Once per turn,you can empower a strike, dealing 1D4 extra damage
• +10ft to speed

Every round you use Kaioken, your maximum hit points is reduced by 1 at the end of of every turn you use Kaioken.

Reduction to your hit point maximum caused by this feature is restored over a long rest.

This ability can only be used once every short or long rest

Super Saiyan - 11th Level

Spending an action and 2 ki point point you power up AND GO SUPER SAIYAN gaining the following benefits

• Attacks deal 1d4 extra damage 
• Kamehameha deals 1D10 extra damage
• Speed increased by +10 ft
• You gain +1 AC
• Gain 15 temporary hit point

This costs 1 ki point at the end of each turn and can only be used once per long rest

This can be used at the same time as kaioken but you recessive one level of exhaustion upon exiting and neither can be used until a long rest

Ultra Instinct - 17th Level

Your literally are the GOAT, using a reaction while being attacked to go ultra instinct

• You can immediately dodge the incoming attack
• You can immediately spend Ki point to regain 1D12 hp per ki spent
• All attacks have disadvantage on you 
• Kamehameha only takes an action and deals 2D10 extra damage
• Your attacks deal 1D8 extra damage
• You gain the extra attack feature
• You gain the sentinel feat

This ends at the end of your 2nd turn after activation, afterwards you gain 3 levels of exhaustion and cannot use any ki ability with the exception of ki blast until the end of your next long rest