Can a person say "And I you"?

Solution 1:

A says to B "I love you"

B says to A "And I you"

Perfectly acceptable. Where is the verb in the latter sentence ? It's in the former sentence and understood to be also in the latter, the repetition is unnecessary. "love" could be replaced by a range of other verbs, such as "hate" or "admire" or "despise"; in fact I can't think of a transitive verb acceptable in the first sentence as a replacement for "love" for which the omission in the second sentence is not acceptable.

Solution 2:

It is perfectly acceptable.

As to "So why did he not reply 'So do I buddy'?", this would be saying "I like me, too". Which may be true in any case, but doesn't express reciprocity. In other words, instead of the two of them saying that they like each other, they would each be saying that they like one of them.

I might say "I enjoy eating crab for dinner." If my dinner companion also likes crab, he might say "So do I." In other words, we both like to eat crab.