Given their low battle stats and HP, Robo Ball should be played incredibly passively and avoid combat as long as it doesn't have any way to fight back. Distancing yourself from opponents can be done with Here and There, Warp panels, or good movement. Players should rely mostly on Bonus panels and Draw Panels.
Robo Ball's HP is very low, meaning it benefits a lot from cards like Saki's Cookie, as well as Heal panels and RegenerationRegeneration Every 5 Chapters, all Units recover 1 HP at the beginning of the Chapter.
Robo Ball's passive makes it incredibly hard to knock down if it ever gets a huge lead, as sometimes opposing players will need to KO it multiple times consecutively in order to prevent it from getting Norma. Players should capitalize on this by attempting to go for as many stars as possible while still laying low
The lowered reward for defeating Robo Ball can work incredibly well when partnered with its Hyper, Reflective Shell, which is an incredibly powerful card that effectively gives it an extra cushion and allows it to hit opponents incredibly hard if used effectively. This can make Robo Ball simply too high-risk and low-reward to be worth bullying and helps deter aggressors. However, depending on the players you are fighting, it is hard to use as a deterrent if you don't actually have it.
You can use tactical damage to Down yourself and prevent losing stars from K.O. The easiest way to do this is to use Damage panels or Damage (x2) panels if they are on the current board, but it can also be done with Cloud of Seagulls or Bloodlust if an opponent brings them into the game. These cards can also be used to apply damage to Robo Ball as well, so it is not too terribly recommended to bring them, as it may just be better to bring other cards instead.
The easiest way to shut down Robo Ball is to prevent it from getting a lead, as its lack of good battle stats really makes it almost unable to use K.O.s to climb up. The easiest way to do this is, as simple as it sounds, to K.O. it before it can get a lead. Many characters can do this, as Robo Ball is very fragile, but high-attack characters like Star Breaker work well
Cards that can harm Robo Ball indirectly, such as Long-Distance Shot, can greatly shut down Robo Ball, as even losing just one HP makes it at high risk of being one-shot or bullied into submission.
Cloud of Seagullsshould work decently for this purpose, as losing 2 HP makes Robo Ball forced to use its poor EVD stat, but Robo Ball can use it to attempt to down itself in order to avoid losing stars, so caution should be taken when adding it to the deck
If players are really struggling taking down Robo Ball, Iru and Sherry (the former being a complete antithesis to Robo Ball's strategy) can ignore (and, in the case of 3 players playing them at once, completely turn irrelevant) Robo Ball's Hyper due to their inability to move first in combat and be targeted by it