Immeasurable speed is something that goes beyond the bounds of the very concept of speed. The difference in speed between two immeasurable characters can be estimated only on the level of existence where the concept of space and time in the conventional sense is irrelevant, but the concept may apply to a higher order.
The reason why simply being outside of space and time not granting you immeasurable speed within space and time is similar to having different types of speed. Just because you can fly at MHS+ speeds doesn't mean you can run at MHS+ speeds. Just because you can swim at High Hypersonic speeds, doesn't mean you can run or fly at those speeds. It's that simple.
So...a character must transcend linear time to have immeasurable speed? I said this before and I'll say it again,
no you do not. Transcending usually means you exist above and beyond the concept. You don't have to be 5-dimensional, unbounded by space or time, or anything like that. You simply just have move at a speed that cannot be measured. Like
Ve said time and time again, our system is so much simpler than we treat it. When we index these characters, what are we doing? Measuring their feats. That's why calcs are important. How do you measure speed? Well, you can ignore it all you want, speed is measured by
dividing the distance covered by how long it took something to cross that distance. S = D/T. D = S x T. T = D/S.
The reason why it's called "immeasurable" is because it
cannot be measured (duh). Within time/without time, it does NOT matter. If it can't be measured using the speed formula, it is by definition,
immeasurable. This of course doesn't include teleportation, cross-universe travel, etc.
I strongly discourage getting rid of anything (be it a rating, profile, whatever) just because it can't be used in a vs match.