I'm just gonna list stuff Mori has and does and let people form their own opinion.
Skill:
We've been here before so I won't beat around the bush. Mori casually copies attacks that took other people years of their life to master. He can adapt to martial arts techniques and has been known to come up with his own brand new techniques to counter them mid battle.
Re-Taekwondo is a martial art that Ikki would most likely not be able to copy. It took
a boy with Precognition an entire day to master a single kick perfectly, seeing into his own future to copy the kick exactly as he saw it, and he still lacked the proper knowledge on how to effectively utilize Re-Taekwondo. 80% of the Korean military that practiced the art exploded from the sheer force of the art, and the art has been stated to be solely used for
Taejin Ji's body.
Bongchim Nah Style Acupuncture is something Ikki definitely can't copy, as it requires you to be somewhat divine to be able to use it. To use it (as a mortal) you have to consume a Divine Pellet. Bongchim Nah, the guy who created the art, spent years in closed practice just to be able to consume one Divine Pellet. It almost killed another guy who ate it, had he not been healed by dragon tears.
Accupuncture can boost Mori's own speed and AP and can make Mori feel no pain. In addition to that, people hit by accupuncture can't heal normally. Nanotechnology and Borrowed Power healing can't cure someone hit by acupuncture. Mind you, Borrowed Power utilizes the soul of a person, so take from that what you will. Acupuncture can also paralyse the opponent.
Also also, the argument that armour will make acupuncture useless is moot when you realize the only time it didn't work was on
someone who's body was made up of the strongest material in both heaven and earth.
Arsenal:
Yeoui weighs as much as a large planet and has 4-B durability from tanking attacks from Gods. While it can't be used effectively without turning into his Monkey King Form, Yeoui still weighs the same and dropping it on Ikki is an instant K.O.
Powers:
Monkey King Mode, can and will one-shot. Mori isn't even hesitent to use it. He's used it whenever he wanted to get rid of a bunch of opponents at once and he's not foreign to the thought of spamming it. However, here he's not fighting many people at once so I think he's less likely to use it. But he will most definitely use it if he feels like he's being overwhelmed.
Also Monkey King Mode allows him access to Geundoowun, which has massive AoE so Ikki being invisible doesn't matter.