I'm not really a big fan of T20 cricket. I think there is something ridiculous about a shortened version of a sport which is meant to be played like chess on legs. Perhaps that opinion means that this suggestion for the Black Caps selectors is somewhat flippant, but here it is anyway.
The team who run out to play Zimbabwe in the 2 T20 matches should be entirely based on performance in the HRV Cup. Reputations should be ignored, as should player development and planning for future matches. The HRV Cup was the first time in many years that every top level cricketer in the country played domestic matches, so as such it is possible to look at the competition as a ten match trial series. Like it or not, Black Caps do not normally turn out for their province. I personally wish they did regularly in the 4 day competition, but I don't hold the purse strings at NZC, so there you go.
There has to be some reward for strong performance against your peers. The Zimbabwe series would be the perfect time to give players who played well a chance to push for selection in more important series, such as the upcoming matches against South Africa. Similarly, it would send a message to the rest of the players in the country that consistency and results are the only things that will give you a chance at higher honours. The new selectors are supposedly abandoning selector intuition as a criterion, but it is fair to say that some recent selections, Tom Latham, Sam Wells, Andrew Ellis, are very much a case of intuition over statistics.
With that all in mind, this would be my team for the T20s against Zimbabwe:
Martin Guptill (504 runs at 72.0 average, strike rate 151)
Rob Nicol (292 runs at 36.5, strike rate 144) + (13 wickets at 19.5 average)
Brendon McCullum (c/wk) (372 runs at 46.5, strike rate 144.7)
James Franklin (270 runs at 38, strike rate 135)
Dean Brownlie (199 runs at 22, strike rate 164)
Hamish Marshall (222 runs at 37, strike rate 147)
Doug Bracewell (181 runs at 154 strike rate) (9 wickets at 7.7 economy rate)
Michael Bates (14 wickets at 20.8 average)
Ronnie Hira (14 wickets at 5.85 economy rate)
Andy McKay (12 wickets at 7.6 economy rate)
Adam Milne (11 wickets at 16.9 average)
So that would mean that out of the current Black Caps T20 squad, I would be dropping Jacob Oram, Nathan McCullum, Kane Williamson, Tim Southee and Colin de Grandhomme. If you look at their performance just in the HRV Cup, they didn't do enough to merit selection. There are some big reputations in that group, and some of them would inevitably come back for the bigger series. However, in the short term, there is merit in selecting the players who have performed in the most recent, and most open trial.