
Before you say character X solos Rimuru...
Make sure character X can interact with:
Law and concept type 1: Attributes are the Laws governing the Principle/Logic of the World, that which preceded existence itself; Elemental Spirits are split off from the Great Spirit of each Attribute, they are Spiritual Lifeforms that embody the laws that governing the world. For instance, Demons are embodying the darkness attribute as they are born from the Great Spirit of Darkness. True Dragons are the Holy Will of Nature and the source of the World, yet True Dragons are also bound by the Attributes as they are associated with them. Spiritual Lifeforms can exist as their conceptual selves they can retain their form at the end of space and time and are thus unaffected by it.
Information type 2: Spiritual Lifeforms can abandon their physical bodies and exist only as pure souls. Information particle and information are the fundamental aspect of Tensura and all things such as Mind, Soul, and Abstract things like Skills are made up of it.
Nonexistent Physiology Type 1 (Nature Type 1, Aspect Type 1, 2, 3, 4 & 5 [Other: Space, Time, Life, Death, Causality & Law] : Demons, essentially being the Elemental Spirits of Darkness, are embodiments of their Attribute, that being Darkness, the same Darkness as that of the Underworld, the same way all Lifeforms share the same nature as the World they are in — They should thus be made of Darkness (Negative Existence Value) the same way all other Spirits are made of Energy of their respective Attribute, split off from their respective Great Spirit [of Darkness])
Beyond-Dimensional Existence Type 1: Information Particles transcend Space and Time, and are unaffected by space and time in any way, which extends to them being able to resist time stop.
Also make sure character X can negate all immortality types and high godly regeneration/resurrection.
Would be also nice if character X has enough of layers into their haxes to bypass Rimuru's resistances.
Post made because I am bored and tired of people saying characters like Asta or Natsu would kill Rimuru when in reality they can't even interact with his core. And no, if your character scales dimensionally higher than Rimuru, they still can't kill him without everything mentioned above. Higher dimensional scaling doesn't automatically grant you ability to interact with everything below.
Unrelated pic because Toyoraro is the CEO of knowballism and he drew an amazing Veldora with his lil bro.