Neutral

Pikachu’s neutral game in this MU uses these 3 tools primarly: Dtilt, nair, and dd grab.

Marth should be used to playing in such a way as to not get his aerials dash dance grabbed, and Marth’s dtilt beat Pikachu’s. If Marth establishes a strong enough presence with dtilt, Pikachu either has to start jumping and (presumably) nairing or just accept getting pushed into the corner.

The ground game in this MU is very similar to Marth/Falcon in that Pikachu is fast and has a threatening grab but cannot adequately answer dtilt (although Pikachu's dtilt is definitely better than anything Falcon brings to the table there). When Pikachu starts nairing, Marth ideally hits him out of it, but that can be very hard to do at times. Side b and jab, much like against Falcon, are very good at stuffing Pikachu nair, but they don't lead to huge rewards directly, so Marth has to learn to leverage the position they grant him. Marth’s biggest punish game conversions are going to come from calling out Pikachu nair with rising fair, but if Marth does that with full drift forward either he must be right about Pika’s nair timing, or eat a huge punish. In other words, a very hard read. So, Marth’s only way to use rising fair (or occasionally nair) semi-safely is to concede a little bit of stage and try to catch Pikachu coming in. This is where Marth can get value out of having Pikachu cornered, because fairing, jabbing, and dtilting in that space is difficult for Pika to deal with.

Another macro point: Marth should not be the primary dash dancer in the Pikachu MU. Marth's DD is incredible, of course, but Pikachu's overshoots are phenomenal and Marth doesn’t get a ton out of grab in this MU unless the player is a TAS robot who can RTC a 2 frame tech in place consistently. That isn't to say grab is bad (look at the pinned messages for both techchasing and uthrow conversions) but against the other overshoot nair master (Falcon) it is not at all unreasonable for Marth to take a stock from a grab at sub 10 percent with 1 read. Pikachu is not like that, and Marth outranges him by such a great margin it would be silly not to try and leverage that. Als an important point, Marth’s dtilt is actually better/safer against Pikachu than Falcon, because it interacts much more favorably with Pikachu's jump. Despite Pikachu actually having faster jumpsquat, his hurtbox is much slower to clear the dtilt hitbox vertically than Falcon's jump, meaning Marth’s risk of getting dtilt jumped over into a big punish is substantially less in comparison. Also worth mentioning is that getting Pikachu naired while crouching is must less of a tragedy for Marth than say, Falcon’s stomp.

Pikachu cross up nairing Marth’s shield is a common enough situation that it warrants addressing too. The main mixup here is that immediate up air from Pikachu after a crossup punishes Marth’s WD/jump out and most of Pikachu’s other options can punish wait/roll. Marth can directly punish Pikachu's full jump up air with full jump bair if Pikachu chooses to full jump up air after the cross up. Pikachu trying to go nuts on Marth’s shield spamming cross ups is very unsafe. Marth can jump or WD out and swing very successfully, and so Pikachu should avoid the wilder repeated nair pressure that is sometimes seen.

When Marth DOES use movement in this MU, Pikachu’s overshoot nair should be the primary concern. Overshoot nair will almost always beat Marth repeatedly dashing forwards and backwards, so Marth should do his best to circumvent this by doing so less and considering how his movement options interact with Pikachu’s nair. In general, it is wisest for marth to move in such a way that Pikachu’s nair places Pikachu in front of Marth on landing, rather than behind. Some tools for this include: Dashback shield stop, WD back, double WD back, and dash back shield pivot WD back. Crouch cancelling the nair is effective as well, so long as Marth winds up facing Pikachu. In terms of forward movement, Marth’s advance should be accompanied by the threat of a hitbox. These tools include run cancel down tilt, wavedash dtilt, RC/WD jab, run up side b, and run up SHFFL fair in place, and run up fade back double fair. All of these options threaten Pikachu’s space relatively safely while giving Marth stage control and keeping him away from the perils of the corner/ledge.

From all of this Marth can distill a general neutral game plan: Use dtilt and jab/side b to take space, and fair/nair (primarily fair) to hold or concede space while attempting to gain a larger opening. All of the above moves are effective corner pressure tools against Pikachu, but Marth must be weary of ledgedash up smash and especially ledgedash nair against sufficiently technical Pikachus.