Okay so here's what we need:
Dunsparce Evolution
From 100/70/70/65/65/45 (Dunsparce) --> 110/90/70/65/65/79 (Evolution) (just enough speed to outspeed Diggersby and make it more viable than Diggersby in some cases).
And this:
Shuckle Pre-evo (to complete screw up LC, as well as lower tiers):
So Shuckle is 20/10/230/10/230/5 so then reduce that down to 15/10/115/10/115/5. With Eviolite, that's 172.5 in either defense (completely uninvested). Like Gligar except even better (except for no Roost Picture a little Shuckle but more Kawaii and with a much smaller total shape and larger proportional eyes.
Also, Mega Magcargo with Water Absorb and change the Fire/Rock to pure Fire. Sprite would look kinda like Grimer, like a Firey slug that just could not be contained by his shell anymore. Also, he is hot enough that he constantly is needing re-hydration (hence the ability). Stats would go from 50/50/120/80/80/30--> 50/50/150/100/150/10. Nice high defenses and Recover. Decent offenses and, let's be honest, this Lava Pokemon wasn't going before anything with that base 30 speed. This base 10 speed ensures it will out-slow most everything in Trick Room. No longer would this mon fear things such as Mach Punch and Aqua jet, either. The Mach Punches are now neutral damage and aqua jet just gets absorbed. I think with an ample moveset of perhaps Recover/Lava Plume/Clear Smog/Amnesia, this little fire slug could become a decent threat, if not in OU, then in one of the lower metas. Anyway, just me rambling about mons that seriously need something else to accompany them.