Different ninja give different buffs. I'll list the ones I remember off the top of my head here.

Note-Buffs can be removed by Han, or someone of the sort, and barriers can be overwritten, so as long as your barrier is in effect, you have the buff. If a ninja isn't listed with a specified attribute, it means both Nin and Attack get the buff.

Auto-Barrier buffers. (These guys make a barrier at the start of the game, lasts 3 rounds) These all give attack and ninjutsu buffs.

Darui-40% to all Lightning and Water Ninja.

Haku [Edo Tensei]-40% to Wind and Water Ninja.

Mei Terumi-40% to Water and Fire Ninja.

Onoki-40% to Wind, Earth, and Fire Ninja.

Danzo-40% to Lightning and Fire Ninja.

Gaara(5th Kazekage)-40% to Wind and Earth Ninja.

Shisui-40% to Lightning, Fire, and Wind Ninja.

Normal Barrier Ninja (Barrier is Mystery)

3* Gaara-40% to Wind Ninja.

3* Sasuke-40% to Lightning Ninja.

Yamato-40% to Earth Ninja.

Jirobo-40% to Earth Ninja.

Haku-40% to Water Ninja.

Anko-40% to Fire Ninja

Hashirama (1st Hokage)-40% to Konoha/Leaf Ninja.

Note-Roshi, Tendo make barriers that have no buffs, Itachi's barrier is only a chakra machine, and shark Kisame's is a mass control one.

Normal buffs-Added on, eventually expire after X number of rounds and can be removed via Han, gnw Temari, or others.

Guy-30% Taijutsu buff to your entire team. (your team only), 3 rounds.

Sasori [Edo Tensei]-30% to 9 Edo Units for 3 rounds.

Mifune-30% to 9 sword users for 5 rounds.

Konan-30% to 9 (Or all, I don't remember) Akatsuki ninja, 3 rounds.

Hashirama Senju (1st Hokage)-30% Nin Buff to your entire side (all 3 teams) for 5 rounds, permanent buff in skillbroken.

Tobirama Senju (2nd Hokage)-30% Tai buff to your entire side (all 3 teams) for 5 rounds, permanent buff if skillbroken.

Jugo-30% to curse mark people, lasts 3 rounds.

Pain-Chikushodo-40% Nin to all Rinnegan units.

Pain-Shurado-40% Tai to all Rinnegan units.

Toroi-20% to any Lightning ninja with a shield.

Killer Bee (7 Sworded Thug)-30% to Jinchuriki, 3 rounds.

Samui-30% to Cloud Ninja, 3 rounds.

Hebihime(Agate)-30%(?) to all...yeah, I don't remember, sorry, but hey, it's Hebihime, she's not even real.

Iruka-30% to Leaf Ninja, lasts 3 rounds

PB Sasuke-30% to up to 9 female ninja, lasts 3 rounds

Then we have people who apply their buffs, but don't expire or are removable by Han.Includes Scaling buffs.

Both Edo Asuma and WB Asuma-30% I think for WB, but for sure Edo for any nin at full hp.

Skillbroken Senju bros, see their listing regarding skillbreaks in the above section.

Kisame, 3rd Ay, others, I don't wanna find them this late at night-X chakra gives X attack and X ninjutsu, varies, I'll get a full list later.

Roshi-gets more Nin (and Defense) every time he's hit by a taijutsu attack

Kage Minato-9% Tai each time he actives flying raijin slash.

Sailor Sakura-gets more attack each time she gets hit.

Jonin Minato-+9% Tai each time he activates his chase.

Edo Yagura, Unreleased-13% everytime he activates his chase...he's sorta broken looking.

2* Sasuke-I think he gives +nin per times hit, low though.

Tayuya-+nin each time hit, probably low

Ukon and Sakon-+tai each time hit, probs low

Deidara-Each time he causes ninjutsu damage, increase damage dealt by 4%

Ameyuri Ringo-12% per lightning nin

Jinin Akebino-60% per skill point, up to 240%....jeez

DW Hinata-13% per female unit

Madara-20% to Konoha Nin

Thanks to MuroiMaNin for the Madara ordeal

I'm not writing anymore until 2018...happy new years (This was written 12/31/2017, 11:37PM)

Only includes offensive buffs, and no buffs like Resistance rinnegan, shields, combo rate from Kinkaku, etc.