I really do find the mid level characters more interesting in bleach, i always want them to exceed expectations. All fights in character (so except for the one fight Ikkaku wil not be using his bankai).
Izuru Kira vs Shūhei Hisagi
Izuru Kira vs Renji Abarai
Izuru Kira vs Ikkaku Madarame
Shūhei Hisagi vs Renji Abarai
Shūhei Hisagi vs Ikkaku Madarame
Renji Abarai vs Ikkaku Madarame
Renji Abarai vs Ikkaku Madarame (Ikkaku willing to use bankai if Renji realeses his)
Izuru vs Renji: I honestly don't know. Renji might be the superior fighter but if Izuru blocks his attack at least six or seven times then his fighting skills are all but useless
Izuru vs Ikkaku: The same result as above althought Ikkaku could by chance one-shot Izuru.
Hisagi vs Renji: Unless Renji uses bankai Hisagi wins
Hisagi vs Ikkaku: Since Ikkaku isn't getting his bankai, Hisagi wins again. However since Ikkaku's a better fighter this can be debatable.
Renji vs Ikkaku: Renji wins since he gets bankai while Ikkaku doesn't
Renji vs Ikkaku: Renji might win but that only if he uses bamboon bone cannon off the bat. In raw power, Ikkaku is the superior I think.
Izuru's zanpukto seems very overpowering. bleach fights are very rarely hugely one sided. Anyone whos not exceptionally fast/skilled (id say were talking captains/vizards/arrancar who specialise in melee) WILL make contact with that weapon and by the time your blades cross 6 times your weapon is weighing a good 40 stone.