Pinning down "Are roulette balls weighted?" is done at the wheel. Roulette looks like pure chance, and it is, but the rules still decide how much any bet costs. A European wheel has one green zero, an American wheel adds a second, and French tables add rules that return half of some losing bets. Knowing which wheel is in play, what each bet pays and what the zero takes is most of what there is to know about playing roulette sensibly.
No strategy can beat roulette, because every spin is independent and every bet carries the same edge. Betting systems change the size and rhythm of stakes, not the odds, and no pattern makes it possible to predict the next number. A player can still be good at roulette in a narrower sense: choosing a single zero wheel, sticking to a budget and knowing when to stop is how to play roulette effectively. Can anyone really win? In a session, yes; over many sessions, the edge does its work.
Licensed roulette wheels are not rigged: they are tested and balanced, and casinos log results so that a biased wheel would show up in the numbers. Balls are not weighted; they are made to a standard size and material, and a worn wheel is replaced rather than exploited. Roulette machines use a random number generator that is checked in the same way and cannot be fixed by the casino. Under licensing regulations there are no illegal bets on the layout itself, although devices that try to predict the ball are banned almost everywhere.
A European wheel has a single green zero, an American wheel adds a double zero, and French tables use the single zero with rules returning half some losing bets.
When zero lands, la partage gives back half of any even money stake, so each of those outside chances costs the player half what it would on an ordinary single zero table.
Choosing a single zero wheel, holding to a fixed budget and knowing when to stop is the only approach that works, since the edge stays constant.
Each spin charges the same share of the stake, so a live table at about forty spins an hour drains a budget far slower than a fast online game.
Neither: each colour holds eighteen pockets, streaks say nothing about the next spin, and zero counts as neither, so even money bets lose on it.