Without boosting: If you take heavy damage and receive two health events, I recommend grappling. Hopefully your opponent has poor submission defence and you can pull one out Clay Guida style. To "Get Good" I recommend you memorize the transition blocks and use this video to help
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With boosting: Select "Online Quick Fight" from the main menu, and invite your friend to the session.
A "health" event is when significant damage is dealt and you enter a stunned state. For this achievement, I recommend the "health event" triggered be directed at the legs. Have your boosting partner press B or A, or left stick and B or A. This will damage the legs until a noticeable health event occurs. After two different leg health events occur, simply take your opponent down and submit them or KO them, should be easy against a live body.