The way to avoid Links UP B is dodge roll back or jump and hit his head where he is vulnerable. The UP B lasts a long time so DO NOT sidestep, because it will still get you and it has one of the most lag times in the game after the move has been acomplished, so punish the LINK after he misses you with it. NOW for the pros, spike and good things about the UP B is that the UP B lasts a long time, but u can get punished, and if the UP B gets u from the tips on the either sides or even a bit off from the tip but close to it, it will spike u diagonally downwards, and its one of the harder spikes to meteor cancel since its sending you diagonally. It has good knockback and does a decent amout of damage, but I would never reccomend to anyone to use the UP B ( SPIN ATTACK) to gain damage, rather spike, take off a stock or push them back so you can recover. NOW the UP B is easy to tech on the ground so always tech when u get hit by hit and DI towards the stage diagonally. Try to also Tech of the wall when you are about to get hit by the SPIN ATTACK and about to get spiked. Basically the UP B (SPIN ATTACK) is a good move with a lot of potential but if used in the wrong situations and wrong times, it will get the LINK player punished, so it has its UPS and DOWNS, in my opinion its a pretty good move overall but since I play LINK I also get pissed when I miss it because I get ***** afterwards : ).