NinjaBossPro is the Gym Leader of Lewisia City's Potion Gym. He is a Tier-5 who knows powerful status moves such as Roid Rage and Pencillin, as well as a great projectile damage source with his very powerful Chemical Bomb. He knows Backstab as well, which allows him to easily counter pusher moves such as WindBlade, and combos well with Roid Rage.
These are the moves that NinjaBossPro uses in combat:
Roid Rage allows him to gain excessive strength when used in combination with Backstab. However, if you go first, he is unlikely to lead with it.
Penicillin allows him to recover about 3 hearts of damage at any point in time. This prevents him from being chipped away at with moves like Miner's Punch. The best counter is to use a status move that delays his moves or prevents them altogether, like Web Shot or Nerves Of Steel.
Backstab is a very, very strong counter to pusher moves, as it allows the player to move (and stay) behind the target. However, if it isn't combo'd with Roid Rage, then even leather armor is sufficient in preventing any sort of damage.
Chemical Bomb is a high damage projectile move that ignores armor, making it the most destructive move in his entire arsenal. Chemical Bomb will, in general, kill you in 3 hits. That being said, if you use a pusher move, such as WindBlade, or a move that moves yourself into a permanent position close to the target, like Backstab, then you should be able to force him to miss/damage himself.
If you beat NinjaBossPro, you will receive:
Ticket to Champion's League