Isn't that what I've been saying? <_>
It's told it's an evasion, but it's shown as a barrier. What we get is an evasional barrier, aka you both have a barrier and evade.
Barrier that evades cannot be broken, but even a half barrier cannot be gone through if it's evasional. Without the other, it wouldn't make any sense. Half a barrier could be circumvented with moves that ignore barriers and defence and hit everyone, while evasion with moves that do not miss. But if things were to go through this half barrier + guarantee a hit, it would go though (such as hail that goes through protect, combined with blizzard that makes it 100% accurate = no barrier or evasion defence) Detect is evasion too, but has no barrier but seemingly prediction, thus smaller amount of pokes learn it (most notably fightning type pokemons). Both being priority moves, the pokemon moves first before your opponent (or predicts), thus near unpenethrable. Even slow pokes like shuckle can do protect with their inner energy, if rattata the rat, defying all odds can thunderbolt people and pidgey can fly trainer around cities like no one's business, not forgetting speed =/= evasion. But it takes quite the skill/stamina/luck to be able to do it twice in succession. Full barriers on pokemon are also shown as screens of light, like barrier, light screen and reflect. Protect is a different animation with different text.