First off, he's a Nonesuch enemy; that's why he's ridiculously strong. Second:
- You might want to go up a level or two; he's a level 6 enemy.
- The stun is a standard Physique check - half your Physique plus 1d20 must equal or exceed half his Physique plus 10. Since he has no way to increase his Physique of 26, that's effectively a check of half Physique + 1d20 >= 23. It also has a 4-turn cooldown.
- The lust attack he uses while you're stunned deals Tease damage, with a base damage of 15-18 the first time he uses it and 20-23 on subsequent uses. Having high Willpower will, as always with lust-based attacks, reduce the damage you take, and wearing airtight armour will prevent him from using it completely.
So, wearing airtight armour is your best bet defence-wise. Offence-wise:
Physically, he has a high Defense of 20 and no resistances or weaknesses, but if you use the same kind of attack (melee or ranged) two turns in a row, he'll negate the second and counterattack, so you'll have to alternate melee and ranged attacks.
Lust-wise, his Lust Defense is a significantly lower 12, and his sexual preferences are fixed:
- Really Dislikes (x2/3 damage from) big breasts (at least DD-cups - only affects chest tease), hyper (size 25+ breasts for chest tease, longest cock at least 18 inches for crotch tease), tail genitals (self-explanatory - only affects butt tease) and baldness (self-explanatory - only affects chest and crotch teases)
- Kinda Dislikes (x0.8 damage from) big butts (at least size 10 - only affects butt tease)
- Kinda Likes (x1.25 damage from) small breasts (C-cups or smaller - only affects chest tease), lactation (self-explanatory - only affects chest tease) and long hair (at least 8 inches - only affects chest and crotch teases)
- Really Likes (x1.5 damage from) feminine (positive Femininity - only affects chest and crotch teases)
Note that these stack multiplicatively, but before damage caps are applied, so if your Tease Skill is high enough, only the Dislikes will matter, and only if they outweight the Likes - and if his preferences are an issue, hip teases will ignore all of them. Additionally, when he's at 80 Lust or more, he'll use a move that reduces his Lust by 50, takes one turn to prepare (during which he does nothing), has a 3 turn cooldown, can only be used twice (since it costs 50 Energy), and either tries to blind you for 2 turns (if you're wearing an airtight suit) or deals 15 base power pheromone damage (if you aren't). So offence-wise, I think lust damage is the better strategy against him than physical damage.