... except against Condoleezza Rice (but I have no clue why they polled her):
43-40 Rice/Clinton
44-43 Clinton/Paul
44-43 Clinton/Huckabee
43-40 Clinton/Bush
45-42 Clinton/Rubio
42-39 Clinton/Christie
46-41 Clinton/Walker
47-40 Clinton/Cruz
44-37 Clinton/Fiorina
45-37 Clinton/Carson
Note: Gravis Marketing, a nonpartisan research firm, conducted a random survey of 1,259 registered voters in Iowa regarding potential matchups [388 Republicans]. The poll has a margin of error of ± 3% [5% for the Republican Primary question]. The total may not round to 100% because of rounding. The polling method was done through IVR, with the raw results weighted by anticipated voting demographics. A full reporting of the crosstabulated results is available upon request.
http://gravismarketing.com/polling-and-market-research/iowa-poll-bush-leads-crowded-gop-field-rice-beats-clinton-head-to-head-43-to-40/