Well, it depends on the fighting game.
In the 2 I gave, CVS2 and EX2, Blanka has access to tools that most of the cast cannot do, and from there he can deal damage that others can't, while being 100% invincible. He's balanced in a way, but he still has access to this kind of ability, more often than it seems.
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These videos are when the full invincibility on all move was discovered, and actually used. It was the final of what was at the time the biggest tournament in the world when it comes to CVS2.
He was able to nearly instakill anyone.
For EX2, I think the latest video was the SF 25th anniversary, not 100% sure and I cannot find it now. Basically, Blanka had the best pokes, the best priorities and he could chain a Super into another Super (the only one to be able to), dealing enough damage to nearly instakill someone.
Lore wise, this Rico is in a completely different league and would destroy Blanka on sight, but there isn't any lore in SF outside of a few fights so...
Would have to dig internet searching for a power ranking of some sort.