Some interesting points here. Sand Stream itself in ADV is certainly not busted, it is the Sand Veil abusers that are rendering games uncompetitive. Complex banning TTar + SV users on the same team may be the optimal route to go, or it may not be. I daresay (without looking at any usage stats) that TTar is the #1 most used mon in the tier, so ultimately what does complex banning really achieve? The pool of viable mons in ADV is certainly more shallow than either of DPP/BW. Hence I would much rather favour a blanket ban on sand veil itself. Lets look at the individual pokemon who get sand veil:On a related tangent, Sand Stream is far more broken than Sand Veil and its removal would result in fewer de facto bans (and no transitivity breaking). SV is only busted when SS has been activated; no one would care about it if you needed to waste a moveslot on Sand Storm to gain the perk for 5 turns (or 8 if you give up the item slot as well). The constant Lefties recovery of GSC flipped into a constant loss of health to sand, and its been a huge factor in ramping up the offensive nature of OU in later gens (seriously, think about how much total damage it does in every game, and without even using a move to make it happen.) It's why Ttar sat in S-Rank for 3 gens (and is still A+, but SS is no longer permanent).
Considering either alternative, banning SV is just odd to me. For the actual topic of ADV, my line of thought is the same. Extending Evasion Clause to prevent using Cact + TTar on the same team is sensible; possibly giving an opposing Cact increased evasion should just be seen as a drawback to using Ttar. Cact and a bunch of other random things getting the boot is unnecessarily extreme, though (and especially weird compared to banning just the #1 mon that's also causing the only actual issues with the ability).
1. Dugtrio - much rather have arena trap
2. Cacturne - only one ability, so it gets banned
3. Gligar - has hyper cutter, so the only loss is to uncompetitiveness
4. Sandslash - only one ability, but totally unused afaik in OU, its loss would be unmissed
So, only Cacturne is really affected by a ban on SV. If anyone has run a viable TTar-less Cacturne team to this date, please let me know.
Nothing at all has changed in terms of the mechanics of Sand Veil from ADV to DPP to BW. Thus, if the ability is banned in the latter two generations, then it should be the case for ADV. Also, strategies that develop in later generations often trickle back into past gens. Look at Heist's swagger aerodactyl for instance. Just because sand veil was not a glaringly obvious issue in the past does not hinder it from being an issue today.Mechanics, Pokemon, moves, abilities, items, etc. all change with each generation. If something that wasn't problematic for generations is suddenly being abused in the current one, why would we need to retroactively "fix" what used to be acceptable? Take Swagger, for example. It's been claused out for the past two gens, but that was never even considered during GSC - DPP. In this case, Prankster's what pushed it over the edge. This sort of thing should always be case-by-case.