Wrong.
It's been that way since Gen 1.
Evasion has always capped at +6.
At least gen III then :P I wasn't sure about gen I and II, so said III to be on the safe side.
Anyways, back on topic.
I noticed that the Item Launcher variant for Flat Battle is missing, so here's the details on it. I haven't had a chance to experiment with it myself, so if I'm wrong, correct me and I'll edit this:
Wonder Launcher Basics
Wonder launcher only works if both players have it enabled, and is available on ladder matches.
Each turn, you gather points from arbitrary criteria (KOs, "positive" type matchups, and damage)
- I haven't been able to find a good list of these.
You get a "Launcher" option, which works like normal items, but only uses wonder item listings.
The Items
All of these work the same as single player, special items are noted. Buff items, just like in single player, go away when switching out (although they probably stay in rotation battles, like any other stat buff).
Thanks goes to Serebii for this list.
1 point
Item Urge - It activates its teammate's item for immediate use when used.
2 points
Potion
3 points
Ability Urge - It activates its teammate's ability when used.
Dire Hit - Raises crit chance by 1 stage
Guard Spec. - Prevents stat reductions on your team for awhile
X Items - There's one for each stat, and one for accuracy
4 points
Super Potion
Ice Heal
Antidote
Awakening
Parlyz Heal
Burn Heal
5 points
Item Drop - Its teammate loses its held item if used.
X Items 2 - Buffs stat by 2 levels
Dire Hit 2 - Buffs crit chance by 2 levels
6 points
Full Heal
7 points
X Items 3 - Buffs stat by 3 levels
Dire Hit 3 - Buffs crit chance by 3 levels
8 points
Hyper Potion
9 points
Reset Urge - It returns its teammate's stat changes to normal when used.
10 points
Max Potion
11 points
Revive
12 points
Ether
X Items 6 - Boosts a stat by 6 stages (maxes it out)
13 points
Full Restore
14 points
Max Revive