  Based on our previous work (Vidotto et al. 2009a), we investigate the effects
on the wind and magnetospheric structures of weak-lined T Tauri stars due to a
misalignment between the axis of rotation of the star and its magnetic dipole
moment vector. In such configuration, the system loses the axisymmetry
presented in the aligned case, requiring a fully 3D approach. We perform 3D
numerical MHD simulations of stellar winds and study the effects caused by
different model parameters. The system reaches a periodic behavior with the
same rotational period of the star. We show that the magnetic field lines
present an oscillatory pattern and that by increasing the misalignment angle,
the wind velocity increases. Our wind models allow us to study the interaction
of a magnetized wind with a magnetized extra-solar planet. Such interaction
gives rise to reconnection, generating electrons that propagate along the
planet's magnetic field lines and produce electron cyclotron radiation at radio
wavelengths. We find that a close-in Jupiter-like planet orbiting at 0.05AU
presents a radio power that is ~5 orders of magnitude larger than the one
observed in Jupiter, which suggests that the stellar wind from a young star has
the potential to generate strong planetary radio emission that could be
detected in the near future with LOFAR. This radio power varies according to
the phase of rotation of the star. We also analyze whether winds from
misaligned stellar magnetospheres could cause a significant effect on planetary
migration. Compared to the aligned case, we show that the time-scale tau_w for
an appreciable radial motion of the planet is shorter for larger misalignment
angles. While for the aligned case tau_w~100Myr, for a stellar magnetosphere
tilted by 30deg, tau_w ranges from ~40 to 70Myr for a planet located at a
radius of 0.05AU. (Abridged)
