  We explore the proposal that the six-dimensional (2,0) theory on the Riemann
surface with irregular punctures leads to a four-dimensional gauge theory
coupled to the isolated N=2 superconformal theories of Argyres-Douglas type,
and to two-dimensional conformal field theory with irregular states. Following
the approach of Gaiotto-Teschner for the Virasoro case, we construct W_3
irregular states by colliding a single SU(3) puncture with several regular
punctures of simple type. If n simple punctures are colliding with the SU(3)
puncture, the resulting irregular state is a simultaneous eigenvector of the
positive modes L_n, ..., L_{2n} and W_{2n}, ..., W_{3n} of the W_3 algebra. We
find the corresponding isolated SCFT with an SU(3) flavor symmetry as a
nontrivial IR fixed point on the Coulomb branch of the SU(3) linear quiver
gauge theories, by confirming that its Seiberg-Witten curve correctly predicts
the conditions for the W_3 irregular states. We also compare these SCFT's with
the ones obtained from the BPS quiver method.
