EVs: 252 HP / 252 Atk / 252 Def / 252 Spc / 252 Spd
- Leech Seed
- Mega Drain
Best I can think of at the moment. Substitute is your first part of stalling. Leech Seed saps your opponent's HP and healing you, therefore healing Substitute damage. Toxic stalls even more, taking more HP off the opponent. Mega Drain is for additional recovery.
Used over Exeggutor because of better bulk and less weaknesses. If you still want Exeggutor, however, the exact same set can be used.