In High 6B, the strongest Tensei Shitara Slime Datta Ken Characters should be above Alte.
Light Novel Diablo starts with his passives (Aura) Death Manipulation Radiation Manipulation ,Confosion Inducement , Fear Manipulation , Sleep Manipulation, Corruption Type 2.
(Continued Way) Thought-Based Powernull, Law Manipulation.
İmmortality Type 4 Negation, Soul Manipulation.
Defansive: High Godly Regeneration ( Information Type 2 ),
Limited Abstract Existence 1 (Embodiment of Laws), Immortality Type 5 (Outside the Concept of Death)
(A lot of Soul (İnformation Type 2) based resistance.)
Reasons:
Alte can't do anything to Diablo.
Diablo destroys him with his passives and thought-based abilities.
The Immortality that Alte has is of no use to him here.
Light Novel Shion doesn't starts with her passives but she has passive (Aura) , Fear Manipulation, Confusion Inducement, and Sleep Manipulation, Corruption Type 2, Radiation Manipulation.
Generally start with this (Thought-Based) Attack Reflection, Reality Warping, Causality Manipulation, Law Manipulation, Fate Manipulation
(Continued Way) Durability Negation, Death Manipulation.
Defensive: (A lot of Soul (İnformation Type 2) based resistance and resistance.
Reasons:
Shion doesn't have as good a physiology as Diablo, but the resistances she has in this key allow Alte to resist anything he has.
Alte can't do anything against Shion's abilities.
Alte's immortality may work the first time, but later on when Shion learns of his ability, She can deal with Alte's immortality.
(All Abstract Things being Information Type 2 İn Tensura )