I'm really sorry to say but... Those sets are just absolutely outclassed in PU... I wouldn't even say that could fill some niches because I can't find a real niche for those (And I usually find even the smallest of those for some pokes)...
Seadra @ Eviolite
Ability: Sniper
EVs: 252 SpA / 4 SpD / 252 Spe
Timid/Modest Nature
- Focus Energy
- Agility
- Surf
- Ice Beam
This set works like super physically bulky, niche simipour with less coverage and no reliable boosts. Lil Critdra has some surprise factor in the use of either of its setup moves depending on the type of team you're playing against and it has enough bulk to setup on most unboosted physical attackers. Also, after one agility (Timid or Modest) it outspeeds the entire tier, barring scarfed mons.
Tropius @ Sitrus Berry/Lum Berry
Ability: Harvest
EVs: 252 Atk / 4 Def / 252 Spe
Jolly Nature
- Dragon Dance
- Leaf Blade
- Aerial Ace
- Earthquake
This set is just stupidly fun to use due to the surprise factor and sweeping potential. So, even with one DD up, it cant outspeed raichu, zeb, or anything over base 101 speed. One DD would technically put it at 331.5 speed, which is enough to outspeed the simi's (dont know if decimals are a thing when calcing speed). It does get some baller coverage moves and EQ for electric switch ins. Also aerial ace does like 78.9 - 93.4% to Rose after +1.
Not saying either of these are viable. Just entertaining. Enjoy
Your Minicritdra is just plain unviable... It needs two turns of setup and it does just roughly a little bit more than other versatile and faster threats like Specs Floatzel and LO Simipour... Also if you likes to setup, just use a Shell Smasher and destroy people with ONE setup turn (Even Huntail is just slightly less bulky considering eviolite, hits harder after a Shell Smash, can go mixed and have Sucker Punch for Priority)... And you are really overselling Seadra Physical Bulk... With that low HP and without any investment a lot of things can still deal good damage (for example Piloswine does have a 85% chance of a 2HKO on Seadra using Earthquake and Sniper + Focud Energy doesn't ensure Critical hits, which means that Seadra should use Scope Lens instead of Eviolite making it even weaker defensively). Also its special bulk is as bad as Tangela's which isn't exactly appealing...
About Tropius... It can be fun to use it since people normally expect a sitrus stall team with Leech Seed, but that doesn't make it exactly viable... Its attack is just lacking (heck... It can't even ensure a OHKO on Simipour with Leaf Blade at +0 which is absolutely hideous considering a Super effective attack and a non existent bulk) and considering one turn of setup, its still slower than other One Turn setup things like the Smashers, the Simis (its a speed tie, but they hit considerably harder after a Nasty Plot Boost), its weak to SR which means that it will usually start the battle at 75% and to make it even worst it doesn't even have a really High power STAB... So, why you should be using this when you can use Fraxure that has a better STAB, is initially Stronger, Faster with nice Coverage on Outrage (or Double Chop), Low Kick and Poison Jab and with a similar bulk but a better typing?
A few days ago I was playing with Huntail... And after using Barbaracle and Carracosta I just felt absurdly stupid... Huntail is a really good Shell Smasher but... Carracosta and Barbaracle are just sooooooo much better, that is stupid to use Huntail... Then I just don't think that setuping a Dragon Dance with Tropius and losing a turn is better than just using Life Orb Simisage...
So... They could be good but maybe for FU or even a little bit lower...