Does five of a kind beat a straight flush?

Answer

Yes. Five of a kind is the highest hand type and is better than a straight flush. Thus five aces is the absolute highest hand in these games. Such a hand is however only possible when using true wildcards. Typically five of a kind is formed with four of one rank and a wildcard, though it may also be formed with two wildcards and three of a rank.

Statistically this ranking makes sense: even with wildcards there are fewer five of a kinds than straight flushes. In a game without wildcards there are 40 straight flushes and exactly 0 five of a kinds. With two wildcards there are 624 straight flushes but only 78 five of a kinds. Thus it is perfectly reasonable that five of a kind is better than a straight flush.