I really can't help to think but Tommy from five seasons of Power Rangers has gotten redundant. In fact, I can't help but think of the fact that these five characters form the dream team.
The first character to be used for Tommy's powers was the late Burai of Zyuranger. However he was a more vicious bad-ass than Tommy ever was. Besides, I kind of find Tommy and Jason's battle to be just too random compared to Geki and Burai as estranged brothers. Sadly he died when his life force got all used up. The younger Burai returned in Dairanger as Kou.
Hmmm this is just funny that Kou is the second counterpart as he is just nine years old. I think some Power Rangers fans who also like Super Sentai after seeing Dairanger after Power Rangers Turbo may berate and say, "HUH?!" with this to the point they'll say "Justin should have been this character!" or "It's Justin disgracing Tommy." But Justin is more tolerable as a roommate than Kou especially for a woman. Kou on the other hand is a little pervert that Lin hates to be with. Also, I think he's the only full-blooded Chinese of the group. The actor played a younger Burai in Zyuranger as well. Hee hee.
Hoshino Gorou of Ohranger would probably be a picture of what a mature Tommy would be, Tommy is almost a picture of a growing Hoshino Gorou prior to the military days. Probably the only one that matched. Both were good in martial arts.
Kyousuke Jinnai- Compared to Tommy Oliver, this guy is hardly organized, funnier and more of a bad-ass all in one. There was nothing much similar between them. However TJ took over Tommy Oliver in Turbo though. :-P
Last but not the least, Asuka of Dino Earth in Abaranger. He has a short but rather interesting backstory especially with his romance with an Evorian namely Mahoro who unlike most forbidden loves, married in the end. In Dino Thunder, Tommy only had an admirer but not his love interest. I find this guy to be more interesting than Tommy ever was maybe because he was from Dino Earth.