What beats a small straight in poker?

The highest starting hand in Texas Hold 'Em is AA.

The highest starting hand in Omaha Hi is AAKK double suited.

The highest starting hand in Omaha Hi/Lo is AA23 double suited.

The highest winning combination of 5 cards is the Royal Flush, a straight from T to A of the same suit. Only when playing with wild cards, the Royal Flush can be beaten by a 5 of a kind.