Not going to lie here: Tsunade gave me THREE Fruit ideas which can be used to sum her up to various degrees.
Not to say each reflects her as an individual best, but each one represents a façade of her but do however present very possible and potentially devastating fruits.
Let's start with the one that LEAST represents her.
FRUIT: Mushi Mushi no Mi, Model: Slug
Like I said, one that least represents her.
She is a slug summoner, so it was a must.
In all fairness, the user would still be a healer, just an unconventional one.
Let me explain, via the benefits of becoming a Slug Zoan (not Gastropoda, since that includes snails).
1. Adhesion to surfaces or opponents via slime
2. Boneless body – more handy then one realizes, especially for infiltration purposes
3. Elasticity – different then boneless since this is limbs extension
4. Enhanced smell – due to the one possible weakness of becoming blind or severely reduce sight (as for real slugs)
5. Scale manifestation – a possible form of defense
6. Saw tongue – secret weapon at close range, especially if it can extend a la 'Alien' style
7. Regeneration – Tsunade needs to look young, so this applies
8. Limited organ relocation – a boneless body, so it's doable to avoid death punctures
9. Projectile Generation – related to next pints
10. Goo Generation
11. Poison Generation
The last two abilities would most likely rely on user eating the necessary herbs, plants, and/or compounds to mix in and generate the required slime for the situation.
Slime which could be used for healing or as a poison.
Like I said, unconventional healer.
Ths use of this fruit would not be a frontline fighter due to being boneless in its hybrid form. Yes, I realize that on some level this is a good thing, but bones provide structure to the body, one which is necessary for power transfer through the body during combat.
For those who don't understand, think about the PROPER form to throw a punch: correct stance, hips and arm twisting in the right motion, and energy transfer from the bottom of the feet, through the body, exiting the fist when it makes contact with the enemy.
Good chance bones are needed for that, regardless of how the muscles of the user rearrange themselves to make up for the lack of bones.
So yeah, the user would be more suited as an assassin or healer, depending on the writer's leanings when using this fruit.
Next fruit.