what is the hardest tense to form in German?

Answer 1

If you had something in mind it was probably the subjunctive, as has been mentioned. But there's a problem with this -- the subjunctive is NOT a tense at all!! It is a "mood" used to speak of uncertain or 'contrary to fact' matters, wishes and such.. as opposed to the more ordinary "indicative" mood that is used for simple statements of fact.

In fact, the very link Ms S provided includes the following:

"The subjunctive is not a verb tense; it is a "mood" that can be used in various tenses. The "past subjunctive". .. gets its name from the fact that its forms are based on the past tense. The Subjunctive I is called the "present subjunctive" because it is based on the present tense. But don't let those terms confuse you: the subjunctive is not a verb tense."

But I DO agree that, if you're talking about the most difficult verb FORMS to get right, the "subjunctive" is where you'll find them.

Answer 2

Probably Konjunktiv II (conditional II):

Wenn ich mehr Geld hätte, kaufte ich mir ein größeres Auto.
(If I had more money, I'd buy a bigger car.)

Here's some info about it:
http://german.about.com/od/grammar/a/konjunktivII.htm

Answer 3

referring to post above :

which is also the most useless tense since really nobody ever uses it...