Both of these have protagonists and villains who can power up!
Gon even does an imitation of Super Saiyan 3 at the end of the Chimera Ant Arc (although that was a one-time deal), and Luffy's Gear Second and Gear Third abilities are pretty straight power ups.
Not to mention Chopper's Rumble Ball enhancements, Sanji's Diable Jambe technique...