Figuring EasyVer problems - problems whose witness can be verified in time independent on the instance size
If I get it right, you are interested in those parameterized problems that can be verified by a bounded-time NTM (running in time $f(k)$ for some function of the parameter). Up to fpt-reduction, these are precisely the problems in the class $W[1]$, see "On the parameterized complexity of short computation and factorization" by Cai, Chen, Downey and Fellows.