as a mixup to the dtilt wd in place or a little forward or back out of run has the similar effect of breaking movement rhythms but functions differently, it isn't as fast but has higher priority and longer duration, so you're not really trying to catch people by surprise with ftilt or threaten with it but more restrict their approaches (especially since you can angle it up as anti-air). there's a certain spacing point (mu dependent of course, this is all assuming pika has less range than the other character which is true for a majority of the cast) pika gets to in the neutral game (the other part of which is spent battling for stage control via movement and projectiles, which i'm not very good at and won't speak about), right outside where you can't react in time to your opponent's quickest approach where he has to:
run away. you can play with teasing this border/baiting with a good DD game. not as good against faster characters like fox sheik falcon who can close the gap.
wd back. good since pika kinda sucks with his back to the opponent minus upair oos mostly
shield. generally not the best option but an important one to consider
spot dodge/prepare to CCC. ...not gonna say plain "no" because that crushes creativity but easily the most situational and therefore least common action
throw out a defensive attack (keep in mind offense can be the best defense and vice versa, by advancing your defense to a threatening position you are also attacking). on the scale of "don't know what opponent is going to do" to "perfect read," these are the best attacks to be mixed up based on a bunch of different factors: dtilt/ftilt/jab aren't very punishable but don't have much payoff besides damage and interruption, dsmash (has more endlag but a higher payoff plus great priority)/upair (if you read their jump it can beat them before their aerial comes out) are punished easier but lead to more stuff, fsmash/upsmash have great payoff but need a pretty damn good read or you get ****ed, and then you need a perfect read for grab lol.
throw out an offensive attack, aka approaching. sh/fh nair good against grounded and aerial chars, sh/fh fair more against more aerial based chars, dash attack is garbage until a very high percent, grab pretty much have to bait a laggy move, and then there's always the running upsmash we love to go for. fh overshoot thunder is interesting lol it's a decent escape at FD if you're backed into a corner because the wall it creates last longer than a lot of people think. but yeah you guys know what you need to do once you actually get in
what separates good players from bad ones is that they can integrate all these options seamlessly and use multiple combinations of them simultaneously to cover the most options and adapt to their opponent's playstyle the best while remaining unpredictable themselves
sorry if all of this is worthless/obvious, but there are plenty of up and comers who read and don't post and could use some of this, and idk writing it down and intellectualizing it helps me understand pika better. this started as a simple ftilt celebration lol well there's some of my general pikachu philosophy. let me know if any of it is blatantly wrong, etc.
For some reason I feel like I should've already known that but I just never actually attempted it enough to be successful until now haha. You just stand on one of the side platforms, full jump and charge your forward B, release it at the right time, and you'll be able to up-b safely on the other side of the stage if you get enough distance 
