Moving while switching arts is something I think playing piano helped me with.
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Anyways, so here's the monado arts from my perspective.
No monado art has a glaring weakness except for Monado Smash, and maybe Monado Shield WITHOUT Advancing Air Slash.
Monado Jump:
You take 1.22x damage. However, your jumping ability makes it easy to avoid attacks and escape from combos. You can be very unpredictable with this art, and you have very good control over the stage. More damage taken if you are hit, but much less of a chance to be hit in the first place.
Monado Speed:
You deal .8x damage. However, you get more hits out thanks to improved grab game, faster air speed, and combos. Your worse shield pushback is mediated by improved cross-ups and aerial mobility (being able to go forward and back easily). Lowered jump height is fine, because your recovery is actually still improved by the air speed.
Monado Shield:
Worse mobility all around. So, just don't move around much; play a defensive game. Rather than hit shields with your worse shield pushback, use your extra shield strength to play a great defensive game. You don't need to approach projectile users anyways; let them stale on your shield. Uhh, you deal less damage, but take less damage yourself. Has an overall effect of slowing the game. Less air mobilty/recovery is somewhat mediated by the less knockback taken. However, hits can string you off-stage. Then, this is mediated either by switching to Monado Jump or using Advancing Air Slash.
Monado Buster:
You deal more damage. 1.4x damage. You take more damage. 1.13x damage. I have seen several different people call Buster risky. No. If you take some hits while in Monado Buster, it's really not that bad. In the long run, 2-4% more damage is not going to matter, especially if Monado Shield is being used well to extend your stock. If anything, the shield pushback makes Buster more safe. Also, of course, the lower knockback is not actually a real downside, because it allows for combos (easy D-throw combos).
Monado Smash:
There's no too much that redeems this art outside of kill percents. Helps against some combos and can get some early gimps. If used defensively, it does help keep people away from you for some time as it sends them farther away. That could moderately help in stalling, but Jump/Shield are better for that role.
Where am I going with this? Well, I think this is important for understanding why decisive arts are so good.