It's all fun and games until it drops a guest. Then it's a misdemeanor.

Juggletron

Trample
Whenever this creature attacks, you may put an art sticker on it.
This creature gets +3/+0 for each item in its art that's not touching Juggletron, another item, or the card frame.

Unfinity

Additionally, the stickers must depict tangible items, so sound effects, thought bubbles, and the like won't count.

Counters are also items that Juggletron can't juggle. They're not part of the art, and Juggletron just can't get a grasp on them. 

If you put name, ability, or power and toughness stickers in Juggletron's art, they'll do what they're supposed to do as stickers, but they aren't items Juggletron can juggle.

In order to count toward Juggletron's power bonus, a sticker must be completely within Juggletron's art, such that no part of the sticker is touching the frame, another sticker, or Juggletron itself. This includes the entire sticker, including the white border.