Sybase (and, I suppose, MS-SQL) lets you create user-defined data types like so:

sp_addtype <typename>, <system type name>
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and you can then use the type in any place where you normally use a system data type. You can also bind rules and defaults to the user-defined data type.

As for going through the database catalog to find the offending column names/types you would do that with a query agains sysobjects, syscolumns and systypes, where sysobjects holds the name of all the objects in the database (in this case the tables i.e. where sysobjects.type = 'U'), syscolumns holds the name of all the columns in a table, and finally systypes holds the definition of the data type for each column.

AFAIK there is no pre-cooked system function or stored procedure that will fetch this information for you, but the query is relatively easy to write.

That being said I agree with Abigail-II - you should really have that data normalized... :-)

Michael