So, here i am, a guy with almost 70% winrate, over 2.30 KD, and S rank last season. My current guide will be about how to get good, and make your character useful in many modes. I currently have about 61% winrate due to Server great optimalization, like Black Screen after won game, bad matchmaking( lvl 13 with lvl 94 WUT XD) but still managed to get highest rank, even after won game that should've got me to S rank faster, i got black screen and lost 3k points for no reason xd

Flag battle= If you decide you wanna go for flag, make sure you have some sort of escape. My ninja is an Attack with= Leaf substitute, which has lowest cooldown. Sharingan- If you are about to get hit by jutsu, or any attack, you will appear in other place, which is good.
And- Leaf Flash, good attack that is hard to counter. As Ultimate jutsu, i like Ultimate of Pain, as it oneshots everyone in it, and is easy to get opponents in it.

If you defend- I suggest Defence type, the one with highest amount of health, and defence. My ninja currently has, Sand Shield, prevents enemies from getting to you, if you stay on flag, they can't get it, until they destroy your shield( takes a little bit) or makes Jutsu like Pulling jutsu, which pulls you to enemy. As well as Snake attack from Mitsuki, Snake Thrust i believe it's name. Plant bombs are useful, since they can stay at flag and 3 of the bombs in same place might kill someone easily. Ultimate Jutsu i choosed was Gaara's Ultimate, Grand Sand Mausoleum.

Support type- Healing and Paralysis, in order to shut down Defence type with jutsu that prevents you from taking flag, or Paralysis and Cherry Bottom Clash if you are defending type/ Katsyu Summon.

KILL ENEMY TEAM. In this mode, you wanna go pretty much ALL OUT, which makes me personally always pick Ranged type, due to it's super high damage, and my own best expierience at it. On this class i recommend- Fireball Jutsu/ Pheonix Flower Jutsu, Super Beast Scroll Lion, try to always use it in the air as then you use it immediately, Kiring, or Totsuka Blade as Ultimate.

Meelee Type- my preferance is- Sharingan, Leaf Hurricane, Planetary devastation.

Defence- Mud Wall, Snake Thrust and as Ultimate Shark Bomb or Sand Mausoleum.

Healing- Cherry Blossom Clash, and Paralysis or any type of Healing Jutsu.

BASE Battle- Defence type= Sand Shield, and Summoning: Toad. Ultimate should be Mausoleum.

Attack- Almighty Push, Sharingan/Summoning: Great Snake Ultimate: Planetary Devastation.

Ranged Type- Lighting Shuriken Net, Summoning: Salamander/Fire Style: Flame Bombs.

Defence: Sand Shield, Snake Thrust/8 Trigrams Palm Rotation. Ultimate: Grand Sand Mausoleum/Earth Style: Earth Pillar Explosion.

Support: Paralysis Jutsu, Cellular Extraction Jutsu. Ultimate: Sealing Jutsu: String Light Formation most preffered by me ^_^

I think this should be most of the things i'd like to recommend on using, always remember that if your team currently for example: 2 meelee 1 Range, you should choose healing type, if you fight on Team Deathmatch, and defence if it's Base Capture or Capture The Flag.

Flag/Base Defence. Good Luck!