My wife has an ancestor named Charles Davies. The 1841 and 1851 Wales censuses as well as his marriage record state that he was born in Flintshire, Wales between 1813 and 1816. A search for his baptismal record (electornic, published indexes, and microfilm) always pulls up the same two Charles Davies born in 1818 or 1821. The problem is our Charles was married in 1835, which would put his age at 17 or 14 respectively. I know that getting married at 14 is very unlikely, but what about age 17? What is the earliest age that was considered proper for a boy to get married in England in the 1800's?
The situation you describe (a UK marriage in 1835) is governed by three Marriage Acts passed in 1753 (26 Geo. II. c. 33), commonly called Lord Hardwicke's act, in 1823 (4 Geo.4 c.76) and in 1824 (5 Geo.4 c.32).
This, and similar legislation, can be read at legislation.gov.uk
You will find a lot of confusion in the discussion of this legislation on the web. My understanding is that, while they did introduce an element of parental involvement in approving a marriage, the Acts left the accepted minimum ages where they were in traditional canon (that is church) law. So it was possible for a girl to marry at 12 and a boy at 14. Even if the parents disagreed with the decision, there were perfectly legal ways in which the marriage could take place.
So in the absence of other evidence, the marriage date does not give you a solid basis to choose between the two possible births.
Researchers with an interest in historical marriage practices in the UK (or a need to cope with its intricacies) might consider the book:
Marriage Law for Genealogists: The Definitive Guide ...what everyone tracing their family history needs to know about where, when, who and how their English and Welsh ancestors married
by Rebecca Probert of the Warwick School of Law and available through Amazon (in print format).
If you believe that you don't need the book, then the author offers a quick quiz on the University website.
Until 1929 the legal age was 14 for boys and 12 for girls
Although marriage at 17 did happen it was not that common (in England and Wales at least) and may have been because they had to, marriage at 14 although possible was highly unlikely unless a family with land or property who wanted to retain assets
The Baptisms you have found are not necessarily the only Charles DAVIES, which is a very common name, particularly in Wales, have you tried other variations such as DAVIS etc The Baptisms you found do they record the birth date or year? Some children were Baptised years after birth, some in adulthood and some were never Baptised at all Check later census years for a mention of a specific birth place