Other creatures have base power and toughness 2/2 and are Bears in addition to their other types.
Because damage remains marked on a creature until the damage is removed as the turn ends, nonlethal damage dealt to creatures may become lethal if Kudo enters or leaves the battlefield during that turn.
If an effect causes a noncreature permanent to become a creature and sets its power and toughness as it does so, that creature will have that power and toughness; it won't be 2/2. Notably, crewing a Vehicle does not set its power and toughness, so a Vehicle will be a 2/2 creature once crewed.
Kudo, King Among Bears's ability overwrites any effects that set a creature's power and toughness. Any existing effects or counters that raise, lower, or switch a creature's power and/or toughness continue to apply to the creature's newly set power and toughness. Any power- or toughness-setting effects that start to apply after Kudo enters the battlefield will overwrite this effect.