While Lumineon is outclassed by basically every other Swift Swim abuser in rain (hey, at least she's better than Luvdisc!), and almost every other Water-type outside of rain, Lumineon's access to Rain Dance, Safeguard, and U-turn gives her a unique niche in the lead position as a Rain Dance supporter. With Lumineon's great Speed and decent bulk, she has few issues getting both Safeguard and Rain Dance up against most leads before U-turning to an appropriate Rain Dance abuser. Leads such as Uxie who attempt to spread paralysis can find their attempts futile due to Safeguard, and will even prove to be setup bait for some Rain Dance abusers. Additionally, fast Taunt leads such as Ambipom and Alakazam fail to do much to her as she can simply U-turn to a strong Pokemon to threaten them, and she can still set up Rain Dance later in the match. To top it all off, once Rain Dance has been used, Lumineon is actually surprisingly dangerous, as rain-boosted Surfs can still deal a large amount of damage to frail sweepers despite Lumineon's pitiful offensive prowess.
Due to Lumineon's interesting Speed, different amounts of EV investment in Speed can be used with varying success. While max Speed is generally ideal to beat max base 90s such as Moltres, fewer Speed EVs can be used if you find that these Pokemon aren't particularly important to outspeed. 176 EVs allow Lumineon to outspeed all the Pokemon at the coveted Base 80 Speed mark outside of rain, which is a great overall mark for Lumineon to be just above. Due to this, it isn't particularly wise to use less Speed EVs than this, as otherwise Lumineon will be outsped by the omnipresent Venusaur. Leftover EVs can be placed in either defense depending on what you want Lumineon to switch in on. If you wish, you may use a Jolly nature with Waterfall instead of the recommended Timid nature and Surf to make U-turn slightly stronger, but this makes Lumineon's offense weaker due to Waterfall's lower Base Power.
Since Lumineon is designed to set up Rain Dance, Pokemon who can use the rain to their advantage are necessary. Traditional Water-type abusers such as Kabutops, Gorebyss, Ludicolo, Omastar, and Qwilfish are all natural candidates due to their blistering Speed and absurdly powerful Water-type attacks under rain. However, since Lumineon herself is a Water-type, stacking your entire team with only other Water-types is less than ideal, since it makes it incredibly easy for a reasonably fast Grass-type such as Sceptile to sweep once the rain has stopped falling. To prevent this from happening, using alternative rain abusers, such as Electric-types with Thunder and Hidden Power Water, in addition to extra Rain Dance users who can cover some major weaknesses are useful. Rotom and Manectric are good choices, with great Speed and Special Attack to fully abuse 100% accurate Thunder with. As for alternative Rain Dance users, Registeel makes a good choice to take on deadly Grass-types while being bulky enough to last throughout the match to keep Rain Dance up.