Is the imamate of someone unable to perform some of the pillars or conditions of prayer valid?

The well-known opinion in the school of Imam Ahmad is that one who is unable to fulfill a condition or a pillar cannot lead in prayer someone who is able. However, the more preponderant view is that this is permissible, and that whoever's prayer is valid, his imamate is also valid, unless there is a text or consensus that contradicts this. This is supported by the Prophet's (peace and blessings be upon him) saying: "If he prays sitting, then pray sitting, all of you." And one who prays sitting is unable to stand, which is a pillar in the obligatory prayer.