Shouldn't bump me from another thread :P But I'll forgive you this time.

Skull Lord and Tainix are gonna be geared similarly. Both need to be fast, and have high-ish acc. Tainix wants to prioritise HP over DEF in terms of defensive stats, while Skull Lord doesn't really care which. Aim for 250+ SPD on them. In terms of amounts of accuracy, it depends on the stage, but 250 is a decent starting point.