If Blitzcrank grabbing from the bush is a problem for you, just buy some wards.
Overall, Blitzcrank is not even a top tier support. The pull is difficult to land, not because it is hard to aim, but rather because good players will hide behind their minion waves. In addition, every thing in his kit revolves around him landing a grab. If you deny him that, he has no use in lane.
Blitz's passive mana shield is only effective for the first few levels, where he might try to cheese you. Since it is based off effective mana, it soon becomes insignificant after a few levels until he catches up on items.
Although Blitzcrank has pretty good AP ratios on his abilities, most people play him support tank, so he shouldn't be doing much damage.
If you want to trade safely with Blitzcrank, just hide behind your minions.
If you see an enemy pick Blitzcrank, tell your support to pick Tresh. Tresh's lantern counters Blitz's pull since you can ride it back to Tresh.