The Blitzcrank build for Support is Shurelya's Battlesong and Glacial Augment. This LoL Blitzcrank guide for Support at Platinum+ on 13.23 includes runes, items, skill order, and counters.
Blitzcrank Counters
52.2%
(+0.3%)
46.5%
(+0.1%)
7.8%
(-0.3%)
29.6%
(+0.5%)
323
(-2)