Um, check one of the posts I linked to. Tokusatsu means, special effects.
There is literally no other definition. If you look at the Wikipedia article,
the term tokusatsu is applied to pretty much anything with special effects.
You sound like you're using the term "tokusatsu" to refer to nothing but shows like Sentai and Kamen Rider. But no, the most successful shows of the industry do not decide what other shows can count. Shows can have different styles of stunts, filming, etc and still count as tokusatsu. For example,
Mega Monster Battle had a brand new method of filming unlike all other shows, but it's still called tokusatsu.
A show can still count as tokusatsu even if the hero doesn't yell transformation words, and the monsters don't make sparks every time they're hit with a weapon. Example: Garo.
Perhaps you're misunderstanding me. I'm not suggesting that the shows are no more than the use of speciall effects, but the term tokusatsu has no more meaning itself than the use of special effects. The term "tokusatsu" carries no more meaning than that. Anything particular about the actual shows is due to the shows themselves doing their thing rather than the fact that they're tokusatsu.